Preheat oven to 325. Butter and flour a 9×13” sheet pan.
In the bowl of your stand-mixer, beat together the sugar, butter, and flour until the mixture is sandy.
Add baking powder, salt, zests and vanillas and beat to combine.
Add eggs, one at a time. Beating for at least 30 seconds between each add.
Add the buttermilk and orange juice and mix to just combine.
Spread into prepared sheet pan. Bake for 35-40 minutes. If using cake pans, check at 30 minutes.