Add the butter and cream to the bowl of your stand mixer. Mix on medium speed with the whisk attachment until the butter and cream combine.

Increase the speed to high, and mix for 3 to 5 minutes until the mixture is light and fluffy, stopping to scrape down the sides a time or two.

Add the vanilla and 2.5 cups of the powdered sugar. Mix on low until combined, and then increase speed to medium and whip for 1 to 2 minutes.

The consistency of the icing is important if you are going to pile it high on a cupcake. It should be a medium consistency. If you mix the batch of icing with a metal teaspoon (the kind you use for dinner) it should stand up straight in the middle of the bowl when it is in the icing. So, you should be able to stir it with a spoon by hand but it should also be sturdy enough to hold the spoon up. If the icing is too thick, add a little cream. If it needs to be a little thicker, add a 1/4 cup of powdered sugar and whip to combine until it's sturdy enough.

Place in an icing bag and pipe on the cupcakes with tip 2A.