Preheat oven to Gas 4 / 160 fan

Grease and line a round sandwich tin with baking parchment

Break the eggs into a large mixing bowl, then add the caster sugar.  Whisk this up for 5 to 6 minutes on full speed until it triples in volume, turns almost white and is very light and fluffy.  I find an electric hand whisk does the best job

Sift the flour into a separate bowl, then sift again a little at a time into your egg mixture.  Fold in each addition of flour into the mixture with a spatula or wooden spoon, being very careful not to knock air out of your egg mix.  Once all the flour is incorporated, spoon into the tin

Bake for 20 minutes until golden on the surface.  Leave to cool

Reduce oven to Gas 2 / 130 fan

Make custard or lemon curd

Spread lemon curd or lemon custard into the recess

Whisk egg whites in bowl until fluffy

Add sugar a little at a time

Remove sponge from tin.  Cut recess into sponge

Spread meringue on top

Place in oven for 45 minutes

Eat