In a large mixing bowl, cream butter, sugar, molasses, egg, and vanilla.

Add dry ingredients and mix until dough is well blended.

Roll into 1 1/2 inch balls; then roll in granulated sugar.

Place dough balls in well-greased mini muffin tins.

Bake at 375 degrees for 9-12 minutes.

Remove from oven and place a miniature Reese's Peanut Butter Cup in the center of each cookie, pressing down gently.

Twist cookie cups to remove from pan.