Preheat oven to 350 degrees F.
In a large bowl, sift the all purpose flour, baking powder, and salt.
In a separate bowl, combine the vegetable oil, eggs, vanilla extract, buttermilk, lemon juice, lemon zest, and sugar.
Add the flour mixture to the wet mixture and mix until well incorporated. Do not overmix.
Distribute the batter amongst 3-8 inch buttered cake pans.
Bake for 20 minutes or until fully cooked through.
Let the cakes cool completely.
To make the cream cheese buttercream, mix the unsalted butter and cream cheese on high speed for 2-3 minutes. Add the powdered sugar, lemon zest, vanilla extract, and milk. Mix for an additional 2-3 minutes on high speed or until nice and fluffy.
Frost the cake and enjoy!