Ingredients For

Cookies

1/2 cup unsalted butter cut into Tablespoon-sized pieces, 113g

2 cups semisweet chocolate chips (340g)

3/4 cups light brown sugar packed (150g)

1/2 cup granulated sugar 100g

2 large eggs + 1 egg yolk room temperature preferred, lightly beaten

1 teaspoon vanilla extract

1 1/2 cup all purpose flour (plain flour) 190g

2 Tablespoon natural cocoa powder

1 teaspoon cornstarch

1/2 teaspoon baking powder

1/2 teaspoon baking soda

3/4 teaspoon salt

Peanut Butter Filling¹

1 1/2 cup creamy peanut butter² (420g)

4 Tablespoon unsalted butter softened

1 1/2 cups powdered sugar (icing sugar) (190g)

1 1/2 teaspoons vanilla extract

2-5 Tablespoons milk³

Instructions

Cookies

Preheat oven to 350F/175C and line cookie sheets with parchment paper.
In a medium-sized bowl, whisk together flour, cocoa powder, cornstarch, baking powder, baking soda, and salt.
Gradually stir flour mixture into butter mixture until completely combined.
Drop cookie dough by rounded 2 teaspoon-sized scoop onto parchment paper, pressing down slightly. Bake in 350F/175C oven for 8-10 minutes, then allow to cool on cookie sheet.

Filling

In KitchenAid or with electric handmixer, cream together peanut butter and butter.
With mixer on low-speed, gradually stir in powdered sugar until completely combined (be sure to scrape down the sides of the bowl so all ingredients are well incorporated).
Stir in vanilla extract.
Add milk, one Tablespoon at a time, until well-combined. Check the consistency at 3 Tbsp and if it is much too thick add the fourth Tablespoon (conversely, if you make it too runny, you may add more powdered sugar).
Spread or pipe (I used an Ateco 848 piping tip) the filling onto the bottom of one of your cooled cookies. Sandwich with another evenly-sized cookie.
Once all cookies have been filled enjoy!