For the orange nut cake, wash the orange hot for the cake batter, dry it and grate the peel.
Beat the egg whites with 45 g sugar and a pinch of salt until stiff, whisk the yolks with the remaining sugar and the orange zest until foamy and fold in the beaten egg whites.
Grate or finely crumble the biscuits and gradually fold in together with the flour, almonds and cashews. Melt the butter and add to the mixture.
Pour the batter into a greased cake pan and place in a preheated oven at 190 °C for about 30 minutes.
For the glaze, wash one orange hot, dry it and grate the peel. Squeeze all (4 pcs.) oranges (should yield about 250 ml) and boil once with the sugar and orange peels.
Then reduce the heat and boil down by about half, then stir in half of the Grand Marnier. Brush the cooled cake with the orange syrup (reserving 2-3 tablespoons).
Mix the fondant with the remaining syrup and liqueur, heat gently and glaze the cake with it.