Separate the eggs, putting the egg yolks in one bowl and egg whites in another. Set aside.
In a large bowl, sift together the flour, sugar, baking powder and salt. Set aside.
In another bowl, mix together the egg YOLKS, water, oil, lemon zest and vanilla.
Pour the wet ingredients into the dry and mix until well combined.
Add the cream of tartar to the egg whites. Using a stand mixer, beat until the peaks are stiff. (This took about 4 minutes in a stand mixer.)
Gently fold the egg white mixture into the batter until combined. Batter will be very light and fluffy.
Pour into an ungreased tube pan and bake on the lowest rack for 50 minutes, or until top springs back when touched.
Immediately invert the pan and let it rest upside down on three glasses.
Allow the cake to cool upside down completely, then slide a knife around the sides and center of the pan to loosen the cake.
Remove the cake to a plate.
To make the lemon glaze, whisk together the sugar, lemon extract and heavy cream. Add additional heavy cream to get desired drizzling consistency.
Drizzle the cake with the lemon glaze.
Store in an airtight container at room temperature.
The calories shown are based on the cake being cut into 12 pieces, with 1 serving being 1 slice of cake. Since different brands of ingredients have different nutritional information, the calories shown are just an estimate.