Stir together with a spatula until uniformly mixed (and a uniform color).
Spread onto cake. Or spoon into a zip-top storage bag, seal, and trim off one corner. Pipe onto cupcakes.
Notes
You can make this up to 3 days ahead. Store in an airtight container in the fridge. Drain off any liquid, stir together, and add to your cake or cupcakes.Dairy-free: Use a dairy-free Greek-style yogurt if needed.You can try making this with 2-4 tablespoons honey instead of confectioners' sugar if desired. (I prefer confectioners' sugar as it makes it more of a traditional frosting consistency. Honey will make a slightly softer frosting.)This makes enough for my Healthy Chocolate Cake or 10-12 cupcakes. (If you like a lot of frosting on your cupcakes, you may want to do 1 1/2 times the recipe!)Try on Vanilla Cupcakes,Chocolate Cupcakes,or Banana Cupcakes.