E.D.
This one holds up well to coloring, just be sure to use a clear vanilla extract to have a whiter frosting. Don't skimp on the beating time - it's what makes it really light and fluffy. And don't try to soften the butter in the microwave - it will change the consistency of the butter and alter the final product.
You can make this a few days ahead of time, just keep it wrapped tightly in the refrigerator and let it come to room temperature before trying to spread or pipe it.
10 tablespoons unsalted butter , softened (1 stick plus 2 Tbls - not margarine)
1 1/4 cups confectioners' sugar
Pinch table salt
1 1/2 teaspoon vanilla extract
1 tablespoon heavy cream
In standing mixer fitted with whisk attachment, beat butter at medium-high speed until smooth, about 30 seconds. Add confectioners' sugar and salt; beat at medium-low speed until most of the sugar is moistened, about a minute. Scrape down bowl and beat at medium speed until mixture is fully combined, about 15 seconds; scrape bowl, add vanilla and heavy cream, and beat at medium speed until incorporated, about 10 seconds, then increase speed to medium-high and beat until light and fluffy, about 4 minutes, scraping down bowl once or twice.
Feel free to email me if you have any questions or problems.