Peel the apples, cut out the core (e.g. with an apple corer). Drizzle apples with lemon juice, place in an ovenproof dish. Roast in the preheated oven (electric cooker: 175 °C/circulating air: 150 °C/gas: level 2) for approx. 15 minutes.
Let it cool down.
Chop nuts. Melt the nougat in a hot water bath, let it cool down for about 15 minutes. Mix nuts and nougat, fill into the apples, press firmly.
Grease a springform pan (26 cm Ø) and dust with flour. Break the chocolate into pieces, melt in a hot water bath, cool down for about 10 minutes. Cream butter, sugar, vanilla sugar and 1 pinch of salt.
Stir in the eggs one by one. Mix flour, cocoa and baking powder, stir in portions briefly. Stir in liquid chocolate briefly. Spread into the mould. Put apples into it, leaving about 1.5 cm free to the edge.
Press something into the dough.
Bake in the preheated oven (electric oven: 175 °C/circulating air: 150 °C/gas: level 2) for approx. 70 minutes (cover after approx. 1 hour if necessary). Remove from the edge of the mould with a knife and allow to cool in the mould.
Dust with powdered sugar.