Preheat the oven to 350 degrees Fahrenheit. Grease the side and base of tin with melted butter and sprinkle a coating of sugar. Swirl for maximum coverage and shake out excess.
Sift together flour and cornstarch in a small bowl and set aside.
In a large mixing bowl, whisk together the salt and egg whites until the consistency reaches soft peaks.
Whisk in ½ cup of sugar until the meringue is stiff and glossy. Set aside.
In a large mixer bowl, combine the egg yolks and the remaining sugar. Whisk until thick and the whisk leaves a ribbon-like trail when lifted.
Finely grate the zest of both lemons into the bowl and briefly whisk. Slowly add the juice of one lemon while the mixer is running on a medium speed.
Gently fold the meringue into the yolk mixture across three batches.
Gently fold the flour mixture into the liquid mixture until just combined.
Transfer mixture into the prepared tin and level the surface. Sprinkle with caster sugar.
Bake for 25-30 minutes, until well risen and golden brown. A skewer inserted into the center should come out clean.
Remove for oven and allow to cool in the tin for one minute. Loosen sponge, if necessary, and gently turn out onto wire rack to cool completely.
Flower Frosting Decorations
Beat egg white until it is fluffy and stiff
Slowly add in powdered sugar, a little at a time, and continue beating until stiff peaks form.
Add vanilla extract and beat until the extract is well incorporated
Color as desired. Use immediately. Cover with a damp cloth to prevent crusting.
Enjoy!!
Notes
Alternative decorating options include fresh fruit and a dusting of powdered sugar.