1/2t lemon zest
2t baking powder
4T cold milk
750g sour apples
100g apricot jam
Preheat oven at 200C.
Whisk butter until fluffy and stir in sugar.
Separate eggs and add egg yolk and lemon zest to butter mixture.
Stir flour, cornflour and baking powder through a sieve and add gradually to milk and mix it well.
Beat egg whites until stiff and fold into the dough mixture.
Fill dough into greased springform tin.
Peel apples, cut in half and carve them to arrange them on the dough.
Bake in a preheated oven at 200C for 50 - 60 minutes.
When still warm, brush with apricot jam and sprinkle with sugar.