Step 1: Prepare Your Baking Pan

Start by preheating your oven to 350°F or 175°C. Line a square baking pan with parchment paper, leaving some overhang on the sides. This makes it easier to lift the brownies out later for clean slicing. Lightly grease the parchment to prevent sticking.

Step 2: Melt the Chocolate for the Brownie Batter

In a heat safe bowl, melt the bittersweet chocolate. You can do this using a microwave in short intervals or over a double boiler. Stir until smooth and glossy, then set aside to cool slightly. This ensures it does not scramble the eggs later.

Step 3: Cream Butter and Sugar for the Brownie Base

In a large bowl, combine the softened butter and granulated sugar. Mix until smooth and creamy. This step helps create the structure and texture of the brownies. The mixture should look pale and slightly fluffy.

Step 4: Add Eggs and Flavoring

Crack in the eggs one at a time, mixing well after each addition. Stir in the salt as well. The batter should become smooth and slightly thick at this stage.

Step 5: Incorporate Melted Chocolate

Slowly pour the melted chocolate into the mixture while stirring continuously. This step gives the brownies their rich chocolate flavor and fudgy texture.

Step 6: Mix Dry Ingredients for the Brownie Batter

In a separate bowl, whisk together the flour, cocoa powder, and instant espresso powder. The espresso powder enhances the chocolate flavor without making the brownies taste like coffee.

Step 7: Combine Wet and Dry Ingredients

Gradually add the dry ingredients into the chocolate mixture. Stir just until everything is combined. Avoid overmixing, as this can make the brownies dense instead of fudgy.

Step 8: Pour and Spread the Brownie Batter

Transfer the brownie batter into your prepared pan. Spread it evenly using a spatula, making sure it reaches all corners.

Step 9: Bake the Brownie Layer

Place the pan in the oven and bake for about 20 to 25 minutes. The brownies should be set but still slightly soft in the center. Remove from the oven and let them cool completely before adding the cookie dough layer.

Step 10: Prepare the Cookie Dough Base

In a mixing bowl, cream together the softened butter, granulated sugar, and brown sugar until smooth. This creates the base of your cookie dough layer.

Step 11: Add Egg and Vanilla

Mix in the egg and vanilla extract until fully incorporated. The mixture should be creamy and slightly glossy.

Step 12: Combine Dry Ingredients for Cookie Dough

In another bowl, whisk together the flour, salt, and baking soda. Gradually add this mixture to the wet ingredients, stirring until a soft dough forms.

Step 13: Fold in Chocolate Chips

Add the semisweet chocolate chips and gently fold them into the dough. This ensures even distribution throughout the layer.

Step 14: Assemble the Layers

Once the brownie base has cooled completely, carefully spread the cookie dough evenly over the top. Use a spatula or your hands to gently press it into an even layer.

Step 15: Final Chill and Set

Refrigerate the assembled brownies for at least 1 to 2 hours. This helps the cookie dough layer firm up and makes slicing much easier.

Step 16: Slice and Serve

Lift the brownies out using the parchment overhang and place them on a cutting board. Slice into squares or bars and serve.