1. Preheat the oven to 350°F (175°C) and line an 8×8-inch baking pan with parchment paper, leaving some overhang for easy removal.

2. In a large mixing bowl, whisk together the olive oil, granulated sugar, and brown sugar until smooth and glossy.

3. Add the eggs, egg yolk, and vanilla extract, whisking for about 1 minute until the mixture becomes pale and shiny.

4. Pour in the melted dark chocolate and Greek yogurt, stirring until the batter is silky and combined.

5. Sift together the cocoa powder, all-purpose flour, and salt, then gently fold into the wet mixture using a rubber spatula. Do not overmix — just until combined.

6. Add the espresso or brewed coffee (optional) to deepen the chocolate flavor and stir gently.

7. Pour the brownie batter into the prepared pan and smooth out the top with a spatula.

8. Bake for 25–28 minutes, or until the center looks just set but slightly soft — the brownies will continue to cook as they cool.

9. Allow the brownies to cool completely in the pan on a wire rack before slicing into squares.

10. Sprinkle with flaky sea salt or add extra chocolate chunks if desired. Enjoy warm or chilled for the ultimate fudgy bite!