Finely chop the walnuts. Separate eggs. Beat the egg yolks, salt and 75 g sugar with the whisk of the hand mixer until creamy. Mix breadcrumbs, flour, baking powder and nuts. Stir the nut mixture and rum into the egg-sugar mixture. Beat the egg whites until stiff, then pour in 75 g sugar. fold the beaten egg white into the nut mixture
Put the mixture into a square, greased and flour-spread cake tin (approx. 22 x 22 cm). Bake the cake in a preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for 20-25 minutes
Take the cake out of the oven, let it cool down for about 15 minutes and turn it onto a cake rack. Let the cake cool down
Cut the cake in half horizontally. Mix mascarpone, quark, espresso, vanillin sugar and 60 g sugar. Spread cream on one half of the cake and cover with the other half. Cover and refrigerate for about 2 hours. Cut into cubes and serve
waiting time approx. 3 hours