• Move your oven rack to the lowest position, and then preheat your oven to 325℉.
• In a large mixing bowl, whisk your cake flour, salt, baking powder, and sugar.
• Slowy, add your lemon juice, grated lemon, water, vegetable oil, and egg yolks; mixed until combine using an electric mixer
• Clean mixer whisks for the next step (below).
• In a separate bowl, beat your egg whites, and cream of tartar until soft white peaks form.
• Slowly fold in your egg whites into your batter
• Pour mixture into an ungreased fluted tube pan and bake for 50-55 mins or until the top of the cake gently springs back when pressed.
• Once cake comes out of the oven, gently press around the edges with a plastic knife to loosen it. 
• Allow the cake to cool for about 45 minutes before frosting.

Frosting the cake

• Once the cake is cooled, and on a cake stand or platter, add your whipped topping to a large piping bag with star tip. 
• Carefully pipe on swirls until the cake is covered. One small tub should be enough for your full cake.
• Add zested lemon to the top of the cake. You can also garnish with additional lemon slices or candied lemon.