Line the bottom of the springform tin with baking paper and grease the sides with butter.
Chop walnut kernels coarsely.
Melt butter and let it cool down a bit.
Mix flour with baking powder and cinnamon.
Beat eggs, sugar and salt until light and fluffy.
Fold the flour mixture into the egg sugar mixture to make a thick sponge batter.
Stir the melted butter into the batter briefly.
Peel 3 apples, cut them into small cubes and mix them with the batter.
Pour the batter into the baking tin and smooth it out.
Peel another apple, cut it into thin slices and spread them on the batter in a fan shape, pressing them into the batter a bit.
Spread the chopped walnut kernels on top and sprinkle it with brown sugar.
Bake the cake in a preheated oven at 356 °F (180 °C) for about 50 minutes, cover it with baking paper during baking if it gets too brown on the surface.
Let the sharlotka with cinnamon and walnut cool and dust with powdered sugar.