In a standing mixer or bowl, combine all ingredients except the colors and M&M’s.
Mix on medium speed or beat the ingredients until your icing is bright white
Add in 1/2 cup of powdered sugar if the icing is a yellow color.
Once you have the icing the color and consistency that you like, split it into 3 bowls and add in a color to each bowl
Cut the Rice Krispie block into small rectangles and dip into the icing.
Set each piece onto baking sheet.
Once they all have been dipped, add 6 M&M’s to the respective colored Rice Krispie bars that has been cut into a rectangular shape.
Let each iced piece sit for at least an hour, so that the icing may set.
Serve!
