STEP 5: Cream cheese frosting. Beat butter and cream cheese on high for 3 minutes. Add in sifted powdered sugar on low speed. Mix in vanilla, salt, and heavy cream until creamy.
STEP 6: Assembly. Freeze cake layers for 10-15 minutes. Add a small bit of frosting to the cake board and place down the first layer. Spread 3/4 of a cup of frosting on top. Repeat until assembled.