(*) For 1 kg of confectionery, accurately grate quinces with a tea towel. Cut quinces unpeeled into eighths and boil in 1 1/2 l water with closed lid for approx. 20 min until soft. Drain water and strain quinces through a sieve (yields approx. 950 g quince puree). Put puree with sugar into a large saucepan and cook for about 40-45 min at low temperature, stirring continuously.
Roast the hazelnut kernels in a heated oven at 180 °C for about 10 min. Grate off the brown skins. Coarsely chop hazelnuts, almonds and pistachios. Stir into the warm quince puree. Spread the mixture about 3-4 cm thick on an oiled baking sheet and cool.
Then cut into squares or rectangles and dry one more time. Melt the cooking chocolate in a water bath and decorate or dip the confectionery pieces as you like. Layer the quince confection with parchment paper in tin cans for storage. It will keep for 2-3 months.