Cream the butter and shortening in a stand mixer set to medium using a paddle blade. Approximately 2 minutes.
Add vanilla extract and 2 tablespoon of water. Mix on medium for 1 minute.
Add ¼ of the bag of powdered sugar. Using the lowest speed, mix until incorporated. Repeat 3 more times until all of the sugar is incorporated.
Add salt and 1-2 tablespoon of water as desired.
Mix on the highest setting for 15 minutes stopping halfway to scrape the bowl.
Notes
The final step of the recipe which calls for mixing on high is what will give the frosting its fluffy bakery quality.There are tons of great ways to use this frosting recipe