Wash the lemon with hot water, grate dry and grate half of the peel. For the dumplings, bring milk, 50 g butter and 40 g sugar to the boil. Add semolina while stirring, bring to the boil and remove from the heat. Mix quark, grated lemon peel and egg with the whisk of the hand mixer, stir in hot semolina mixture. Let the mixture cool down and chill for about 30 minutes
Squeeze the lemon. For the sauce, wash the quinces hot and rub the furry surface. Peel and quarter the quinces, remove the core. Cut the quinces into small cubes and immediately mix them with 3 tbsp lemon juice, apple juice and 70 g sugar in a saucepan. Cut the vanilla pod lengthwise, scrape out the pulp. Add pod and pulp to the quinces, bring to the boil, cover and cook over low heat for about 30 minutes.
Form approx. 12 dumplings from the dumpling mixture, adding just under 1 tsp. cranberries in the middle of each dumpling. Bring plenty of lightly salted water to the boil, add the dumplings and let them simmer at low heat for about 10 minutes
Melt 50 g butter, fry breadcrumbs in it until golden brown. Stir in cinnamon and icing sugar. Drain the dumplings, arrange and sprinkle with the breadcrumbs. Season quince-vanilla sauce with sugar, fold in remaining cranberries. Serve the sauce with the dumplings