With your ingredients ready, it’s time to start baking. Follow these step-by-step instructions to create your own batch of delicious blonde brownies.

Step 1: Preheat and Prepare

1. Preheat your oven to 350°F (180°C).
2. Grease a 9×13 inch baking pan and line it with parchment paper to make removal easier later on.

Step 2: Chocolate Chip Cookie Layer

3. In a large bowl, mix together softened butter, brown sugar, and granulated sugar until well combined.
4. Add the egg, egg yolk, and vanilla extract to the mixture and mix until smooth.
5. Gradually incorporate the all-purpose flour and salt, stirring until just combined.
6. Fold in the chocolate chips.
7. Spread the cookie dough evenly into the prepared baking pan.

Step 3: Oreo Layer

8. Arrange the Oreo cookies on top of the cookie layer, pressing them down slightly to fit snugly.

Step 4: Brownie Layer

9. In a microwave-safe bowl, melt the chocolate and cubed butter in 45-second intervals, stirring between each, until smooth.
10. Allow the chocolate mixture to cool for about 5 minutes.
11. Whisk in the granulated sugar and eggs until well combined.
12. Gradually fold in the all-purpose flour, cocoa powder, and salt until just combined.
13. Pour the brownie batter over the Oreo layer, spreading it evenly.

Step 5: Baking

14. Bake the layered dessert for 37-45 minutes or until a toothpick inserted into the center comes out clean or with a few moist crumbs.
15. Let the brownies cool completely in the pan, about 4 hours, before lifting them out using the parchment overhang and slicing into 18 slices.