In the microwave, melt the chocolate in 15 second intervals. Let it cool slightly.
8 oz Semi-sweet chocolate
In a mixing bowl, sift the flour and cocoa powder. Add in baking powder and salt.
1 cup All-purpose flour, ⅓ cup Dutch process cocoa powder, 1 ¼ teaspoon Baking powder, 1 teaspoon Salt
Using a mixer, beat the butter, brown sugar, and sugar on high for 2 minutes. Add in the melted chocolate. Beat on high for 1 minute. Add in vanilla, eggs, and egg yolk. Beat on high for 1 minutes. It will be light and fluffy.
½ cup Unsalted butter, 1 cup Brown sugar, ⅓ cup White granulated sugar, 2 teaspoon Pure vanilla extract, 2 Eggs, 1 Egg yolk
Add in the dry ingredients. Mix on low until just combined.
Preheat oven to 350°F. Line 2 cookie sheets with parchment paper. Chill the dough for 20 minutes.
Use a 3oz cookie scoop. Scoop the dough and bake 6 cookies per cookie sheet. Bake for 13-15 minutes.
Let the cookies sit for 5 minutes before transferring to a cooling rack. Cool completely.