Preheat oven to 350 degrees. Unwrap peanut butter cups from foil so they are ready to insert into cookies right after they come out of the oven.

Cream together butter, peanut butter, brown sugar, and white sugar. Add eggs, vanilla, and baking soda. Once incorporated, slowly add in the flour and mix just until the flour disappears.

Fill mini muffin tins ¾ full with dough. Bake for 8-10 minutes. Once out of the oven, immediately place a mini Reese’s peanut butter cup in center of each cookie. Cool for 5 minutes and remove from muffin tin. Continue to cool cookies or place in freezer for 20 minutes to allow peanut butter cup to harden.