Set the butter out to allow it to reach room temperature overnight or at least two hours before using.
Put all ingredients in a large bowl and use a hand-mixer to mix the frosting until it is smooth.
Make color bright white
Put a drop of blue food coloring on a spoon. Use a tissue corner to absorb nearly ¾ of it off. You want only the tiniest smear of blue to remove the yellow tinge and make your frosting bright white.
Hand mix the frosting again until the blue is completely mixed in. If the color is still yellowish in your eyes, add a spec more food coloring. But realize at some point, if you keep adding blue coloring, you might turn your white frosting blue to be careful.
To keep it soft, put a soaking wet paper towel over the bowl until ready to frost. This will keep the frosting soft for about 10 minutes so plan your baking around this window.
Store this frosting in the refrigerator for two weeks. To use it, let it sit at room temperature until it is soft.