Pre-heat oven to 350F (180C). Grease and flour a 9 inch (23 cm) bundt pan or 8 inch (20 cm) cake pan.
In a medium bowl whisk together the flour, baking powder and salt.
In a medium bowl beat until stiff peaks appear the 3 egg whites.
In a large bowl beat the 4 yolks and sugar until light and creamy (about 3-5 minutes). Then add the vegetable oil, limoncello and zest, beat until smooth.
Stir the flour mixture into the yolk mixture and combine, then gently fold in the egg whites until combined. Spoon into prepared cake pan. Bake for approximately 25-30 minutes or until toothpick comes out clean. Let cool before dusting with powdered sugar. Enjoy!