Start with the uncolored white frosting first. In a bowl beat the softened butter until light and fluffy, about 2 minutes.
Add 1 cup of confectioners sugar and mix on low until combined with the butter.
Add the remaining 1 ½ cups of sugar, the vanilla extract and milk or cream to the bowl.
Turn the mixer on low and slowly beat the sugar until combined.
Turn the mixer on high and beat for 3 minutes until light and fluffy.
Remove the white buttercream frosting to a small bowl with a lid. Place the lid on and set aside.
Add the next stick of butter to the mixer (no need to wash the bowl at this point).
Repeat the previous instructions.
Once the frosting is done add about 12 drops of blue gel food coloring.
Beat until the food coloring is mixed in well.
Remove the blue frosting from the mixing bowl and place in a smaller bowl with a tight fitting lid.
Wash and dry the mixer bowl well before the next batch of frosting.
Repeat the previous instructions for making the buttercream frosting only, this time, add about 12 drops of yellow gel food coloring to the finished frosting.
Mix well and place in a small bowl with a tight fitting lid.