In same 2-quart saucepan, melt chocolate chips and remaining 1/2 cup peanut butter over low heat, stirring constantly. Divide chocolate mixture evenly on top of peanut butter mixture in each cup (about 1 teaspoon each). Sprinkle crushed granola bars over top of each cup. Refrigerate until set, about 1 hour. Using pointed knife, remove from muffin cups before serving.