Perhaps the simplest frosting to make.
Combine in a medium bowl and beat together on medium speed:
Add and beat until smooth, starting with the smaller amount of liquid:
If the frosting seems too thick, add more liquid a few drops at a time to reach a smooth, spreadable consistency. If it seems too thin, allow the frosting to sit for 15 minutes. These frostings tend to thicken on their own over time. If it is still too thin, add more powdered sugar. To store, cover the surface of the icing with plastic wrap. This keeps for up to 3 days at room temperature or for up to 3 weeks refrigerated. Soften and stir or beat until smooth before using.