Step 1

In a large bowl or stand mixer fitted with paddle attachment, cream together softened butter and shortening until fluffy and well combined.

Step 2

Add the powdered sugar, vanilla extract, and salt. Mix until well blended. The frosting will be very stiff at this point.

Step 3

Slowly mix in the heavy cream on low speed. Once it is fully mixed in, increase the speed to high and beat for 5-7 minutes, scraping down bowl occasionally. The frosting should be very white and fluffy, like a bowl of whipped cream.