INGREDIENTS
1 1/2 cups unsalted butter, softened
4 cups powdered sugar
2 teaspoons vanilla extract
2 tablespoons heavy whipping cream
1/4 teaspoon salt
Seeds of one vanilla bean pod (optional)
PREPARATION
In a large bowl, whip the butter with an electric mixer on medium-high speed until light in color and creamy, about 8 minutes.
Add 2 cups of powdered sugar and mix on low speed until incorporated. Add vanilla extract, salt, and vanilla bean seeds (if using) and mix until combined.
Add 2 more cups powdered sugar and mix on low until incorporated, then add cream and continue mixing until combined.
Increase mixer speed to high and beat until frosting is fluffy and light, 3-5 minutes.
Spread on cupcakes, cake, or just a spoon, and enjoy!
From: http://12tomatoes.com/best-vanilla-buttercream-frosting/