Ingredients:

Cake:
2 1/2 C cake flour
1 1/3 C sugar
1 Tbsp baking powder
1 tsp salt
1/2 C vegetable oil
4 large eggs, separated
1/2 C Limoncello liqueur
1/4 C fresh squeezed lemon juice
2 Tbsp lemon zest
1/2 tsp cream of tartar
Frosting:
1 C softened butter
2 lbs powdered sugar
4 Tbsp Limoncello liqueur
3 Tbsp fresh squeezed lemon juice
1 Tbsp lemon zest
1 small lemon sliced thin

1. Separate eggs, reserving whites.  Mix all cake ingredients, except egg whites and cream of tartar in stand mixer for 3 minutes.
2. Beat egg whites and cream of tartar until stiff. Fold into cake mixture.
3. Grease, flour and line bottom of 3-  9 inch cake pans with parchment circles. Fill pans with 1/3 of batter.
4. Bake at 350º for about 15 minutes until just set but not browned. Cool in pans. Invert on wire racks.
5. Beat butter and powdered sugar together adding Limoncello, lemon juice and zest to make a creamy consistency.
6. Frost between layers stacking to form a three layer cake. Frost sides. Place in refrigerator to set. Garnish with lemon slices.