In large bowl, beat marshmallow creme, butter and powdered sugar on low speed until blended. Beat in enough milk, 1/2 teaspoon at a time, to make frosting spreadable. Spread over tops of cupcakes. Divide chocolate bar into rectangles. Cut each rectangle diagonally in half and place on top of each cupcake. Top each cupcake with bear-shaped cracker. After frosting has set, store loosely covered.