In a large mixing bowl, combine the sugar, brown sugar, cocoa powder, melted butter, and vegetable oil. Beat for about 2 minutes, then add egg and vanilla extract.

Add the flour, baking powder, and salt to the butter mixture, stirring just until combined.

Chill dough for about 30 minutes.

Preheat oven to 350 degrees F. Line a cookie sheet with parchment paper or silicone baking mat.

Remove cookie dough from refrigerator and roll into 12 equal-sized balls. Place on baking sheet.

Flatten each cookie dough ball to 1/4 inch thickness. Bake for 10-12 minutes.

While the cookies bake, make the filling by beating the peanut butter, powdered sugar, and softened butter together until well combined. Roll into 12 peanut butter balls. Refrigerate for at least 5 minutes.

Remove cookies from oven and immediately make an indent in the center of each. Cool for 5 minutes.

Place a peanut butter ball into each indentation of the cookies. Melt chocolate chips and spoon over peanut butter balls. Allow to set.