Heat oven to 350. Grease 24 muffin cups.
In medium bowl, mix brownie mix, oil, water and eggs. Divid batter among muffin cups. Bake13-18 minutes or until centers are set and test done. Cool 30 minutes. Run knife around edges and remove from muffin cups.
In microwaveable bowl, microwave vanilla chips uncovered on Meium 30 to 45 seconds, stirring every 15 seconds, until melted. Cool slightly.
In medium bowl, beat powdered sugar , butter, milk and food colors on medium speed until fluffy. Stir in melted vanilla chips. Spoon frosting over cooled cupcakes; top each with a candy bar.