Roughly chop the chocolate. Melt the fat and chocolate in a small saucepan over low heat while stirring. Let it cool down a little bit. In the meantime, cut apples in half, peel and remove the core. Cut apples into large cubes.
Sprinkle with lemon juice. Mix eggs, sugar, vanilla sugar and salt with the whisk of the hand mixer until creamy. Add chocolate mixture and stir in. Mix flour, baking powder and gingerbread spice and stir in as well. Dab apple cubes dry and carefully fold into the mixture. Fill everything into a greased and flour-dusted rectangular springform pan (35 x 23 cm). Bake in the preheated oven (electric cooker 175 °C/ convection oven: 150 °C/ gas: level 2) for about 40 minutes. Take the cake out of the oven, place on a cake rack and let it cool down. Mix icing sugar, cinnamon and egg white with the whisk of the hand mixer to a smooth glaze.
Fill everything into a greased and flour-dusted rectangular springform pan (35 x 23 cm). Bake in the preheated oven (electric cooker 175 °C/ convection oven: 150 °C/ gas: level 2) for about 40 minutes. Take the cake out of the oven, place on a cake rack and let it cool down. Mix icing sugar, cinnamon and egg white with the whisk of the hand mixer to a smooth glaze. Cover the cake with the mixture and let it dry. Cut the cake into approx. 20 pieces and decorate with apple slices if desired
waiting time approx. 3 hours