Rich & Fudgy Guinness Brownies

If you love dark, malty flavors in a dessert, these Guinness brownies are a treat worth making. The recipe starts by simmering Guinness Draught Stout until it is reduced and concentrated, which gives the brownies a deep, roasted flavor without adding excess liquid to the batter. The reduced stout goes into a thick, shiny batter made with melted butter and semi-sweet chocolate, and the brownies bake up fudgy and rich. A Guinness and espresso frosting on top makes them even more special.

The recipe makes 16 to 20 brownies in a 9-inch square pan. Prep takes about 45 minutes, including reducing the beer, and the brownies bake for about 35 minutes. Because they need to cool completely before frosting, the total time is around 3 hours. They are perfect for St. Patrick’s Day, but they are rich and satisfying any time of year. Below you will find the full recipe, tips, storage guidance, and answers to common questions.

Why You’ll Love These Guinness Brownies

• Fudgy, rich, and dense, with a thick, shiny batter
• Made with reduced Guinness Draught Stout for a deep, concentrated flavor
• Melted semi-sweet chocolate and butter give a truly fudgy texture
• A creamy frosting infused with more reduced Guinness and espresso
• An optional pinch of espresso powder in the batter deepens the chocolate flavor
• Made in a single 9-inch pan, with an easy lift-out method for neat squares
• Keeps for up to a week at room temperature, so they are great for making ahead

What Do Guinness Brownies Taste Like?

These brownies taste like very chocolatey brownies with a slightly malty, roasted undertone. Reducing the Guinness concentrates the stout’s flavor and takes the edge off, so the beer deepens the chocolate rather than tasting strongly of beer. The texture is fudgy and dense, with a thick batter that bakes into a rich, moist crumb.

The frosting adds creamy sweetness and a little more of that Guinness and coffee flavor. Espresso powder in the frosting, and optionally in the batter, enhances the chocolate notes. Together, the brownies and frosting make a grown-up, indulgent dessert.

Recipe Overview

• Prep time: 45 minutes (including reducing the Guinness)
• Cook time: 35 minutes
• Total time: 3 hours, including cooling
• Oven temperature: 350°F (177°C)
• Pan: a 9-inch square baking pan
• Yield: 16 to 20 brownies

The method has three parts. First, simmer the Guinness until it has reduced to 2/3 cup and let it cool. Second, melt the butter and chocolate, whisk in the sugar, 1/2 cup of the reduced Guinness, the eggs, vanilla, flour, salt, and optional espresso powder, and bake. Finally, once the brownies have cooled completely, beat together the frosting using the remaining reduced Guinness, spread it on top, and cut the brownies into squares.

Ingredients

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For the Brownies

• 1 bottle (11.2 to 12 ounces / 330 to 355 ml) Guinness Draught Stout
• 3/4 cup (12 tablespoons; 170 g) unsalted butter
• 2 bars (4 ounces each; 226 g total) semi-sweet chocolate, coarsely chopped
• 1 1/4 cups (250 g) granulated sugar
• 3 large eggs, at room temperature
• 1 teaspoon pure vanilla extract
• 1 cup (125 g) all-purpose flour, spooned and leveled
• 1/2 teaspoon salt
• Optional: 1/2 teaspoon espresso powder

For the Guinness Frosting

• 1/2 cup (8 tablespoons; 113 g) unsalted butter, softened to room temperature
• 2 cups (240 g) confectioners’ sugar
• 2 to 3 tablespoons reduced Guinness (from the first step)
• 1 teaspoon espresso powder
• 1/2 teaspoon pure vanilla extract
• 1/4 teaspoon salt

Ingredient Notes

Guinness Draught Stout

The recipe uses one 11.2 to 12 ounce (330 to 355 ml) bottle of Guinness Draught Stout, which is simmered down to 2/3 cup. Reducing the beer concentrates its flavor and prevents too much liquid from going into the batter, which would make the brownies cakey instead of fudgy. Note that some alcohol may remain after simmering, so keep this in mind when serving the brownies to children or anyone who avoids alcohol.

Semi-Sweet Chocolate

You need two 4-ounce bars (226 g) of semi-sweet chocolate, coarsely chopped. The chocolate is melted with the butter, which gives the brownies their fudgy, dense texture. Use chocolate that you enjoy eating on its own.

Butter

The brownies use 3/4 cup (170 g) of unsalted butter, and the frosting uses another 1/2 cup (113 g) that must be softened to room temperature, so it beats smooth.

Sugar and Eggs

Granulated sugar, 1 1/4 cups (250 g), sweetens the batter. Three large eggs at room temperature bind everything together, and room temperature eggs mix in more smoothly.

Flour, Salt, and Vanilla

One cup (125 g) of all-purpose flour, spooned and leveled, keeps the brownies dense. Spooning and leveling means you lightly spoon the flour into the cup and scrape off the extra, rather than scooping it straight from the bag. Salt and pure vanilla extract round out the flavor.

Espresso Powder

Espresso powder is optional in the batter but included in the frosting. It does not make the brownies taste like coffee. It simply deepens the chocolate and pairs nicely with the stout.

Confectioners’ Sugar

Two cups (240 g) of confectioners’ sugar make the frosting creamy and sweet. You can add a splash of milk if you would like the frosting a little thinner.

Equipment

• A small saucepan, for reducing the Guinness
• A 9-inch square baking pan
• Aluminum foil or parchment paper, for lining the pan with an overhang
• A large microwave-safe bowl, for melting the butter and chocolate
• A whisk
• A handheld or stand mixer with a whisk attachment, for the frosting
• A toothpick, for testing doneness
• A cooling rack
• A cutting board and a sharp knife

Variations and Substitutions

The recipe above is the tested version. The ideas below are only suggestions, and they have not been tested here.

• Espresso powder: It is optional in the batter, so you can leave it out of the brownies if you prefer.
• Frosting thickness: Beat in a splash of milk if you would like a thinner frosting.
• No frosting: The brownies are fudgy enough to enjoy plain if you would rather skip the frosting, though the frosting is a big part of the recipe’s appeal.
• More chocolate brownies: If you love fudgy brownies, try our Classic Fudgy Brownies or our Espresso Fudge Brownies.

Step-by-Step Instructions

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Step 1: Reduce the Guinness. In a small saucepan, bring the Guinness to a boil over medium-high heat. Once boiling, reduce the heat to medium and let it simmer until it has reduced to 2/3 cup (160 g or ml), about 12 to 15 minutes. Set it aside to cool for at least 10 minutes. You will use 1/2 cup (120 g or ml) in the brownies and the rest in the frosting.

Step 2: Prepare the pan and oven. Preheat the oven to 350°F (177°C). Grease a 9-inch square baking pan, or line it with aluminum foil or parchment paper, leaving an overhang on the sides so you can lift the finished brownies out. Set the pan aside.

Step 3: Make the batter. Place the butter and chopped chocolate in a large microwave-safe bowl. Melt them in 30-second increments, whisking after each, until completely smooth. Whisk in the sugar and 1/2 cup (120 g or ml) of the reduced Guinness until completely combined. Whisk in the eggs and vanilla extract. Finally, whisk in the flour, salt, and espresso powder, if you are using it. The batter will be thick and shiny. Pour or spread it evenly into the prepared pan.

Step 4: Bake. Bake for 32 minutes, then test the brownies with a toothpick inserted into the center of the pan. If it comes out coated with wet batter, the brownies need more time. If there are only a few moist crumbs, they are done. Keep checking every 2 minutes until you see moist crumbs. The brownies in the source recipe take about 35 minutes.

Step 5: Cool. Remove the pan from the oven and place it on a cooling rack. Let the brownies cool completely in the pan before frosting or cutting.

Step 6: Make the frosting. In a large bowl, using a handheld or stand mixer fitted with a whisk attachment, beat the softened butter on high speed until completely smooth and creamy, about 2 to 3 minutes. Add the confectioners’ sugar, beating on low at first and then increasing to high speed. Once the mixture is creamy and combined, beat in 2 tablespoons of the reduced Guinness, the espresso powder, vanilla extract, and salt. Taste it, and add the remaining reduced Guinness if needed. If you would like the frosting a little thinner, beat in a splash of milk.

Step 7: Frost and cut. When the brownies are cool, lift them out by gripping the parchment overhangs and transfer them to a cutting board. Spread the frosting over the cooled brownies. Use a sharp knife to cut them into squares.

Step 8: Store. Cover and store any leftover brownies at room temperature for up to 1 week.

Tips for Success

• Reduce the Guinness first. Simmer it down to 2/3 cup and let it cool for at least 10 minutes before using it.
• Line the pan with an overhang. Foil or parchment makes it easy to lift the brownies out for cleaner cutting.
• Melt gently. Heat the butter and chocolate in 30-second increments, whisking after each, until completely smooth.
• Measure the flour correctly. Spoon and level it so the brownies stay fudgy instead of dry.
• Test with a toothpick. The brownies are done when a toothpick shows only a few moist crumbs, not wet batter.
• Check every 2 minutes after 32 minutes. Ovens vary, so keep checking until you see moist crumbs.
• Cool completely. Let the brownies cool fully in the pan before frosting or cutting, or the frosting will melt.

How to Know They’re Done

At 32 minutes, insert a toothpick into the center of the pan. If it comes out coated with wet batter, the brownies need more time. If it comes out with just a few moist crumbs, they are done. Do not wait for a perfectly clean toothpick, because that would give you a drier brownie. Keep checking every 2 minutes. In the source recipe, the brownies take about 35 minutes.

What to Serve With Guinness Brownies

These brownies are rich, so a small square goes a long way. Serve them with a cup of coffee, a glass of cold milk, or a scoop of vanilla ice cream. For a St. Patrick’s Day dessert table, pair them with our Guinness Chocolate Cake and our Baileys Irish Cream Brownies.

Storage

Cover and store leftover brownies at room temperature for up to 1 week.

Freezing

The source recipe does not cover freezing, and we have not tested it.

Common Mistakes to Avoid

• Adding unreduced Guinness. The extra liquid can make the brownies cakey and the flavor weaker.
• Adding hot Guinness to the batter. Let the reduced Guinness cool for at least 10 minutes first.
• Overheating the chocolate. Melt it in 30-second increments and whisk after each.
• Overbaking. Look for a few moist crumbs on the toothpick, not a completely clean one.
• Frosting warm brownies. The frosting will melt and slide. Wait until they are completely cool.
• Scooping the flour. Spoon and level it to avoid adding too much.
• Using cold eggs or butter. The recipe calls for room temperature eggs and softened butter in the frosting.

Frequently Asked Questions

Why do you reduce the Guinness?

Simmering the Guinness concentrates its flavor and prevents too much liquid from going into the batter, which helps keep the brownies fudgy and dense.

How much reduced Guinness do I need?

Reduce the bottle to 2/3 cup. You will use 1/2 cup in the brownies and the rest in the frosting.

What size pan do I use?

A 9-inch square baking pan.

How many brownies does the recipe make?

The recipe makes 16 to 20 brownies.

Is the espresso powder necessary?

It is optional in the brownie batter, and the frosting uses 1 teaspoon.

Do the brownies contain alcohol?

The Guinness is simmered and baked, which reduces it, but some alcohol may remain, so keep that in mind when serving them.

How do I know when the brownies are done?

Insert a toothpick into the center. If it comes out with only a few moist crumbs, they are done. If it comes out coated with wet batter, they need more time.

How long do they keep?

Cover and store them at room temperature for up to 1 week.

Recipe Background

Stout and chocolate are a natural pair, because the roasted, slightly bitter notes of dark beer echo the flavor of cocoa. Guinness Draught Stout is the best-known Irish stout, and baking with it has become a popular tradition around St. Patrick’s Day. Reducing the beer first is a common technique that gives you the flavor without too much liquid.

This recipe is adapted from the Guinness Brownies by Sally McKenney of Sally’s Baking Addiction, written here in our own words with the same ingredients, amounts, and method.

Share Your Creation

Did you make these Guinness brownies? Leave a comment below and tell us how they turned out. Did you add the espresso powder to the batter? Did you save them for St. Patrick’s Day? Your tips and photos help other readers make the recipe their own.

Conclusion

These rich and fudgy Guinness brownies combine reduced stout, melted chocolate, and a creamy espresso frosting into a deeply flavorful dessert. Reduce the beer, melt the chocolate and butter, bake until a toothpick shows moist crumbs, and let them cool completely before frosting. Slice them into squares and enjoy them any time you want a rich, grown-up chocolate treat.

More Delicious Recipes You’ll Love

• Guinness Chocolate Cake – The Ultimate Rich and Moist St. Patrick’s Day Dessert
• 9 Irresistibly Decadent Baileys Irish Cream Brownies That Melt in Your Mouth
• Classic Fudgy Brownies
• Espresso Fudge Brownies
• Ultimate Crinkle Top Brown Butter Espresso Brownies (Irresistibly Fudgy & Decadent )

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Nutritional Information

Nutrition is an approximate estimate per frosted brownie, calculated from standard ingredient values and assuming the recipe is cut into 18 brownies. The original recipe does not list nutrition, and actual numbers will vary with the brands you use and how you cut the brownies.

Nutrient	Amount per Serving
Calories	320
Carbohydrates	41g
Protein	2g
Fat	17g
Saturated Fat	11g
Cholesterol	65mg
Sodium	106mg
Fiber	1g
Sugar	34g

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