1 cup (2 sticks or 226 grams) unsalted butter, at room temperature
1 pound (about 4 cups or 450 grams) confectioners' sugar
3 tablespoons (45 ml) heavy cream
1 tablespoon vanilla extract
1/4 teaspoon salt

In a large bowl, or the bowl of a standing mixer, whip the butter for 6 minutes on medium speed, until the butter is light in color and creamy.

Add the sugar and cream and mix on low speed until combined, about 1 minute. Stir in the heavy cream and vanilla. Increase mixer to medium speed and whip the mixture for another 8 minutes, until the frosting is very light and creamy.