Step 1

Preheat oven to 325°F. Arrange the oven so you can bake the cake on the lowest rack. Set aside a a 10- inch tube pan (Angel Food Cake pan).

Step 2

In the bowl of your stand mixer fitted with the paddle attachment, sift together the flour, baking powder, sugar, and salt.

Step 3

In a small bowl whisk together the egg yolks, water, oil, vanilla, and lemon zest. When combined, add this into the bowl with the flour mixture. Mix on medium-low speed until combined and smooth, scraping the sides of the bowl as necessary.

Step 4

Place the egg whites in a separate large mixing bowl with the cream of tartar. With the whisk attachment or a hand mixer, beat the egg whites on high speed until stiff peaks form.

Step 5

Fold the egg whites into the batter using a rubber spatula until combined. Spoon the batter into the un-greased tube pan.

Step 6

Place the pan on the lowest rack and bake for 50 minutes, or until golden and set. Cake will spring back when pressed lightly.

Step 7

When the cake is done, immediately invert the pan. I like to place the pan on a wine bottle upside-down. This allows the pan to cool without trapping steam underneath, while not allowing the cake to deflate.

Step 8

Allow the cake to cool for at least an hour.

Step 9

When cooled, run a butter knife around the sides of the cake to release it from the pan. Gently lift the cake out. Run the knife under the cake to release it from the bottom cake pan. Place the cake on a platter.

Step 10

In the bowl of your stand mixer fitted with the paddle attachment mix together the butter, powdered sugar, lemon zest, and lemon juice. Turn the mixer up to medium speed and beat for 1-2 minutes until creamy, scraping the sides of the bowl as necessary,

Step 11

Spread the frosting on top of the cake.