Heat oven to 375°F. In large bowl, mix cookie mix, butter and egg with spoon until soft dough forms.
Shape into 36 (1 1/4-inch) balls (about 1 tablespoon each); place in ungreased mini muffin cups. Press indentation in centre of each with end of wooden spoon.
Bake 8 to 10 minutes or until light golden brown around edges. Immediately repeat indentation into centre of each cookie with end of wooden spoon to create 1-inch opening, cleaning off end with paper towel when needed. Cool in pan 15 minutes. Remove to cooling rack; cool completely.
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.