This decadent dessert is light, fluffy, and uses no butter or oil at all!
The cake base is made with egg whites and a little flour, which makes it unbelievably light, and the custard filling is deliciously lemony and a perfect partner for the angel cake.
It takes a little time to make, but your patience will be rewarded! A perfect treat for a summer’s afternoon or a party.
Separate the eggs, and place the egg whites in a large bowl. Let stand at room temperature for 30 minutes if the eggs have been refrigerated.
Meanwhile, line a 15x10x1-in. baking pan with parchment paper; lightly spray paper with cooking spray or rub with a little butter, and set aside.
Preheat oven to 350F/160C fan/gas mark 4. Add vanilla and cream of tartar to egg whites. Beat on medium speed until soft peaks form.
Gradually beat in sugar, 2 tablespoons at a time, until stiff, glossy peaks form and sugar is dissolved.
Fold in flour, about 1/4 cup at a time. Spread batter into prepared pan. Bake for 15-20 minutes or until cake springs back when lightly touched. Cool 5 minutes.
Turn cake onto a clean kitchen towel dusted with powdered sugar. Gently peel off parchment paper.
Roll up cake in the towel Swiss roll style, starting with the short side.
Cool completely on a wire rack.
In a large saucepan, combine sugar and cornstarch. Whisk in water until smooth.
Cook and stir over medium-high heat until thick and bubbly – don’t stop stirring. Continue cooking for 1 minute. Remove from heat.
Crack your egg in a small bowl and lightly beat. Stir a small amount of the hot mixture into the egg and slowly add the egg mixture to the to the pan, stirring constantly.
Bring to a gentle boil and pull off heat. Gently stir in lemon juice and peel.
Let cool down until room temperature, then fold in whipped cream a little bit at a time.
Unroll cake carefully and spread filling to within 1/2″ of edges.
Roll up again – this bit can get messy, as the custard may seep out of the ends.
Remove any excess custard with a palette knife or spatula. Place seam side down on a serving plate. Sprinkle with powdered sugar, slice and serve.
Take care not to over-whisk the egg whites – whisk only until they form soft peaks before adding the sugar. Over-whisking causes the egg whites to collapse and become liquid again.