Spoon frosting into resealable food-storage plastic bag. Cut off corner of bag. Gently insert cut corner of bag into indentation in each cookie cup. Squeeze bag to fill opening, about 1 teaspoon per cookie cup. Cut each truffle in half with small serrated knife, using a gentle sawing motion. Place truffle half on top of frosting, cut side down; drizzle with cookie icing, and immediately sprinkle with candy sprinkles.