Place the powdered sugar in a large bowl. With a hand mixer, beat the sugar on low for a minute to break up the lumps. Add the butter and cream cheese, and beat on low to medium low until the mixture is crumbly.
Gradually add the vanilla and milk, beating the frosting until desired consistency.
Divide the frosting into two smaller bowls. Tint the bowls with gel icing color to desired shade. Stir well to blend.
Frost the brownies with a generous amount of icing, alternating colors. Using a wooden skewer or knife, create a swirl pattern in the frosting.
Top with desired sprinkles and candy.
Cut into squares and enjoy.