For the syrup, put 250 ml water, 250 g sugar and cinnamon in a pot, bring to the boil and simmer open for about 20 minutes. Then stir in 25 g butter. Let it cool down for about 20 minutes, stirring several times. Coarsely chop the walnuts. Peel and quarter apples, cut out the core and dice apples
Mix 250 g butter, 200 g sugar, vanillin sugar and salt with the whisk of the hand mixer until creamy. Stir in the eggs one by one. Mix flour and baking powder and stir in alternately with the milk
Place the dough on a greased, floured fat pan of the oven (32 x 39 cm), smooth it down. Dribble about 1/3 of the syrup onto the dough, pull through lightly with a fork, smooth again if necessary. Spread apples on top, press lightly. Sprinkle with nuts and drizzle another third of the syrup over it
Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for 25-30 minutes. Remove from the oven, place on a cake rack and allow to cool. Add the remaining syrup and drizzle over the cake as desired
Waiting time approx. 10 minutes