Wash the quince thoroughly, peel, quarter and cut out the core. Cut the flesh into slices. Mix lemon juice, 250 ml water, 75 g sugar and quince slices, bring to the boil in a small pot, cover and cook over a low to medium heat for 15-20 minutes until soft. Remove the quince slices with a skimmer, let them cool down and cut into cubes
Chop chocolate and nuts separately. Lightly roast the nuts in a pan without fat, remove. Melt butter and 200 g chocolate in a small pan
Beat the eggs and 150 g sugar with the whisk of the hand mixer until creamy. Mix flour, baking powder and baking soda. Stir the fat-chocolate mixture into the egg cream. Alternately stir in flour mixture and milk. Stir in quince cubes and nuts. Pour the dough into a greased, floured box form (approx. 2 litres capacity, approx. 30 cm long) and smooth it down. Bake in a preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for approx. 60 minutes
Remove the cake from the oven, let it rest on a cake rack for about 30 minutes, then turn out of the tin and let it cool down. Melt 100 g chocolate and coconut fat over a warm water bath. Coat the cake with the chocolate and let it set. Dust with cocoa
waiting time approx. 1 1/2 hours