Using your stand mixer fitted with paddle attachment or using your hand mixer, beat the room temperature butter and shortening together on medium speed till they are pale, light and fluffy, around 5-6 minutes.
Reduce the speed to low and gradually add the confectioners sugar. Add 1/2 cup at a time, increase the speed of the mixer so that it gets fully incorporated with the butter and then add more sugar. Scrape the bowl from sides as required.
Add vanilla and pinch of salt and combine until well-incorporated.
Add heavy cream and whip at medium-high speed until light and fluffy (around 2-3 minutes).
Adjust the consistency according to your requirement. Add more heavy cream for a thinner frosting, add more confectioners sugar for stiff frosting.