Put 30 walnut halves aside. Coarsely chop the remaining walnuts. Separate eggs. Cream fat, vanilla sugar and 150 g sugar with the whisk of the hand mixer. Stir in egg yolks one after the other. Mix flour and baking powder and stir into the mixture.
Finally stir in the chestnut puree and walnuts. Beat the egg whites until stiff, adding 150 g sugar. Fold the beaten egg white into the chestnut mixture. Spread the mixture on a greased and floured baking tray. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 45-50 minutes. Roast walnut halves in a pan without fat, remove. Caramelise 4 tablespoons of sugar, add nuts and cover with them. Remove the nuts and place them on a piece of baking paper or aluminium foil. Peel oranges so that the white skin is completely removed. Cut oranges into 30 thin slices. Take the cake out of the oven, let it cool down and cut it into 30 pieces.
Roast walnut halves in a pan without fat, remove. Caramelise 4 tablespoons of sugar, add nuts and cover with them. Remove the nuts and place them on a piece of baking paper or aluminium foil. Peel oranges so that the white skin is completely removed. Cut oranges into 30 thin slices. Take the cake out of the oven, let it cool down and cut it into 30 pieces. Place an orange slice and a caramelised walnut half on each piece. Whipped cream tastes good with it