In a mixing bowl, add the room temperature soft butter and mix it on medium with the paddle attachment for 2-3 minutes.
With the mixer running on low, add the powdered sugar a little at a time by the spoon full. Combine completely before adding the next spoon full.
When all of the powdered sugar is added, turn the mixer to high and whip for 3 minutes, or until the buttercream is super light and fluffy.
Add the koolaid flavors to the buttercream and mix until combined completely.
Fill into a piping bag and pipe onto each macaron shell.