Coat 1-3/4-inch muffin cups with nonstick cooking spray; set aside. Cut dough into six equal pieces. Cut each piece into four equal slices. Place each slice in a prepared cup.
Bake 9 minutes or until edges are lightly browned and dough is slightly firm. Remove from oven. Indent each cookie shell with the back of a 1/2-teaspoon measuring spoon. Bake 2 minutes or until edges are firm. Cool 15 minutes. Remove shells from cups. Cool.
Place chocolate pieces and condensed milk in a heavy small saucepan; stir over medium heat until chocolate melts. Spoon filling into each shell. If desired, sprinkle with peanuts.