Mix the butter and cream cheese on medium speed until no lumps remain. Do not over beat before the sugar was added or may end up with a runny frosting.
Add vanilla, salt and lemon zest and mix until combined.
Gradually add powdered sugar until desired sweetness and thickness is reached. Scrape down the sides of the bowl and beat until smooth.
Assembling the Cake:
Place one layer of cake onto serving plate and top with thin layer of lemon cream cheese frosting. Place blueberry cheesecake layer and top with thin layer of frosting. Finally, top with second cake layer and frost cake with remaining frosting. Decorate with lemon wedges and fresh blueberries if desired. Refrigerate for at least 45 minutes before cutting or else the cake may fall apart as you cut.
Store in the fridge.
