Preheat oven to 350 F. Prepare a cookie sheet by lining it with parchment paper, then set it aside to make the cookies.

In a medium mixing bowl with a handheld electric mixer, cream together softened butter, peanut butter, and both sugars until fluffy. Beat in egg, egg yolk, and vanilla extract.

Mix in flour, baking soda, and salt until just combined. Fold in chocolate chips and ¾ of the chopped peanut butter cups.

Using a medium cookie scoop, scoop balls of dough onto the sheet leaving about 2 inches between each cookie. Top all the dough balls with the rest of the chopped peanut butter cups.

Bake for 12-14 minutes or until golden brown and the peanut butter cups are perfectly melted.