Light and Fluffy Vanilla Buttercream Frosting
Make sure the butter and heavy cream are at room temperature. The butter should be soft enough to bend without breaking but not so soft that it's melting. Do not warm it in the microwave.
Whip the butter with an electric or stand mixer until it's creamy and noticeably lighter in color. It should lighten up and become a pale yellow.
Start adding the powdered confectioners sugar into the whipped butter, make sure it is sifted and free of lumps and start the mixer out on low so that the powdered sugar doesn't go everywere! Gradually increase the speed of the mixer. Add about half of the rest of the powdered sugar then mix it for 3-5 minutes. Then add the remaining powdered sugar and mix it for another 3-5 minutes until it becomes light and fluffly.
Mix the sugar in very well before adding the heavy cream. The frosting will be quite thick but the cream will loosen it up a bit and the frosting will become silky and lighter in color.
Add in the vanilla, salt, and half of the heavy cream. Beat the frosting for three minutes then give it a stir and test the consistency. Add more cream, if needed, and beat for another 3-5 minutes. If the frosting is too loose and not thick enough, add in more powdered sugar until it's the right consistency.
The frosting should be soft and spreadable but not so loose that it doesn't hold its shape.