Preheat oven to 375F degrees.

In a large mixing bowl, whisk together the flour, baking soda, and salt; set aside.

In another large mixing bowl, use an electric mixer to cream together the butter, peanut butter, granulated sugar, and brown sugar until fluffy.

Beat in the egg, vanilla, and milk until smooth, then add the flour mixture and mix well.

Roll the dough into 40 ¾-inch balls and place each into an ungreased mini muffin pan.

Bake at 375F degrees for 8 minutes. Do not overbake. Remove from oven and immediately press a Reese’s Cup into the center of each cookie.

Chill the cookies in the refrigerator or freezer until the chocolate is set. Use a butter knife to pop each cookie cup out of the pan.