Mix:

1/2 c. peanut butter
1/2 c. white sugar
1/2 c. brown sugar
1/2 tsp. salt
1 egg
1/2 tsp. vanilla
1 1/4 c. flour
3/4 tsp. baking soda

Roll into balls and place in 1 1/2 inch muffin tins. Bake 8-10 minutes at 375 degrees. Immediately press small Reese's peanut butter cup into center of each cookie. Let set 10 minutes before removing cookies from tin.