Old-School Peanut Butter Sheet Cake – Incredibly Moist & Comfortingly Classic (Feeds a Crowd!)

Old-School Peanut Butter Sheet Cake is the kind of dessert that instantly takes you back. The smell alone — warm peanut butter, buttery batter bubbling away in the oven — feels like a hug from the past. Thank you for being here, truly. Recipes like this are the ones that carry stories, laughter, and a few sticky fingers sneaking corner pieces before the frosting sets.

This isn’t just cake. It’s potluck magic. It’s Sunday supper dessert. It’s that handwritten recipe card tucked into grandma’s cookbook.

And before we dive in, make sure you subscribe to our email list so you never miss a comforting, nostalgic bake like this one.

Overview of Recipe Content

What Is Old-School Peanut Butter Sheet Cake?

Old-School Peanut Butter Sheet Cake is a soft, tender peanut butter cake baked in a large sheet pan and topped with a warm, pourable peanut butter frosting that seeps slightly into the top — creating the most irresistible finish.

It’s perfect for:

• Church potlucks
• Family reunions
• Bake sales
• Birthday parties
• Anytime you need to feed a crowd

If you love peanut butter desserts like my Peanut Butter Twix Pie https://poulef.com/peanut-butter-twix-pie/ or this rich Peanut Butter Cup Cheesecake https://poulef.com/peanut-butter-cup-cheesecake/, you’re going to adore this old-fashioned classic.

Why You’ll Love This Cake

• Ultra-moist texture
• Bold peanut butter flavor
• Warm frosting poured right over hot cake
• Easy, one-bowl batter
• Feeds 15–20 people easily

What It Tastes Like

It’s tender and fluffy but still rich. The cake itself is soft and slightly nutty, while the warm frosting melts just enough to create a silky, peanut buttery layer on top. Every bite is creamy, sweet, and deeply comforting.

Ingredients

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• 2 cups all-purpose flour
• 1 ½ cups sugar
• 1 teaspoon baking soda
• ½ teaspoon salt
• 1 cup unsalted butter
• 1 cup water
• 1 cup creamy peanut butter
• 2 large eggs
• ½ cup buttermilk
• 1 teaspoon vanilla extract

For the Warm Peanut Butter Frosting:

• ½ cup unsalted butter
• ½ cup creamy peanut butter
• ¼ cup milk
• 3 cups powdered sugar
• 1 teaspoon vanilla extract

Tools You’ll Need

• 10×15 inch jelly roll pan (or 9×13 for thicker cake)
• Saucepan
• Mixing bowls
• Whisk
• Rubber spatula

Substitutions & Additions

• Add ½ cup chopped peanuts for texture.
• Swap buttermilk for regular milk + 1 teaspoon vinegar.
• Sprinkle mini chocolate chips on warm frosting.
• Add a drizzle of melted chocolate for flair.

How to Make Old-School Peanut Butter Sheet Cake

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Step 1: Preheat & Prep

Preheat oven to 350°F. Grease your sheet pan and set aside.

Step 2: Mix Dry Ingredients

In a large bowl, whisk flour, sugar, baking soda, and salt.

Step 3: Heat Butter Mixture

In a saucepan over medium heat, combine butter, water, and peanut butter. Stir until melted and smooth. The smell right here? Pure nostalgia.

Bring just to a gentle boil, then remove from heat.

Step 4: Combine

Pour hot peanut butter mixture over dry ingredients. Stir gently until combined.

Add eggs, buttermilk, and vanilla. Mix until smooth but don’t overwork it.

The batter will be slightly thin — that’s exactly what we want.

Step 5: Bake

Pour into prepared pan and bake 18–22 minutes, or until a toothpick inserted comes out clean.

Do not overbake — we want moist and tender.

Step 6: Make the Warm Frosting

While the cake bakes, melt butter and peanut butter in a saucepan.

Add milk and bring to a gentle simmer.

Remove from heat and whisk in powdered sugar and vanilla until smooth and pourable.

Step 7: Frost While Warm

Pour frosting over the hot cake immediately after removing from oven. Spread gently with a spatula.

The frosting will settle and slightly soak into the top layer — that’s the magic.

Let cool before slicing.

What to Serve with Peanut Butter Sheet Cake

This cake pairs beautifully with:

• Cold milk
• Fresh berries
• Vanilla ice cream
• Hot coffee

For a full dessert table, serve alongside Chocolate Chip Cookie Bars https://poulef.com/chocolate-chip-cookie-bars/ and Salted Caramel Brownies https://poulef.com/salted-caramel-brownies/.

And don’t forget to pin this cozy classic on Pinterest at https://www.pinterest.com/poulefrecipe/!

Tips for Making It Perfect

• Pour frosting while cake is hot — timing matters.
• Use creamy peanut butter (not natural) for best texture.
• Don’t overmix once flour is added.
• For thicker cake, bake in a 9×13 pan and increase time by 5–7 minutes.
• Let cool fully for clean slices.

Storage Instructions

Room Temperature: Store covered for up to 3 days.
Refrigerator: Keeps 5 days — bring to room temp before serving.
Freezer: Freeze unfrosted cake up to 2 months. Add fresh frosting after thawing.

General Information

Sheet cakes became popular in mid-century American kitchens because they were simple, affordable, and perfect for gatherings. Peanut butter desserts, in particular, became staples thanks to their comforting flavor and pantry-friendly ingredients.

This cake is a beautiful example of practical baking turned into something truly special.

Frequently Asked Questions

Can I make this ahead?

Yes! It tastes even better the next day once flavors settle.

Can I use crunchy peanut butter?

You can, but it changes the texture slightly.

Why is my frosting thick?

If needed, add 1–2 tablespoons warm milk to loosen it.

Can I halve the recipe?

Yes — bake in an 8×8 pan and adjust baking time to 20–25 minutes.

Is this like Texas sheet cake?

Very similar method, but peanut butter flavored instead of chocolate!

Conclusion

This Old-School Peanut Butter Sheet Cake is soft, nostalgic, and comfort baked into every bite. The warm frosting alone makes it unforgettable.

If you love peanut butter desserts, you’ll also enjoy Peanut Butter Twix Pie https://poulef.com/peanut-butter-twix-pie/ and Peanut Butter Cup Cheesecake https://poulef.com/peanut-butter-cup-cheesecake/.

Bake it once, and I promise — it’ll become your go-to for gatherings big and small.

Interactive Elements

Did you make this cake? Leave a comment and star rating below — I love hearing your kitchen stories!

Snap a photo and tag it on Pinterest at https://www.pinterest.com/poulefrecipe/ so I can see your delicious creation!

Nutritional Information (Approximate Per Serving – 18 Servings)

Nutrient	Amount
Calories	390 kcal
Carbohydrates	45g
Protein	6g
Fat	21g
Saturated Fat	11g
Sugar	35g
Fiber	1g
Sodium	210mg

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