Grease a high tart mould (4 cm high, 26 cm Ø, no lift-off base!; springform pan also not very suitable). Sprinkle the bottom of the mould with brown sugar. Spread 25 g butter in flakes on top. Peel apples, core them with an apple corer and cut them in half. Cut the round side of the apples slightly several times.
Sprinkle apples with 3 tablespoons of lemon juice. Place them in the mould with the round side down, close together. For the dough mix 150 g butter, sugar and salt until creamy. Stir in eggs one after the other. Mix flour and baking powder, stir in briefly. Stir in yoghurt, 3 tablespoons lemon juice and zest. Put the dough on the apples and stir carefully until smooth. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for 45-60 minutes on the lower rack (test with sticks!). Let the cake rest on a cake rack for about 5 minutes. Then carefully turn out of the tin and let it cool down.
Stir in yoghurt, 3 tablespoons lemon juice and zest. Put the dough on the apples and stir carefully until smooth. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for 45-60 minutes on the lower rack (test with sticks!). Let the cake rest on a cake rack for about 5 minutes. Then carefully turn out of the tin and let it cool down. Dust with icing sugar. Whipped cream tastes good with it
2 hours waiting time