Mix together the yogurt, quark, 120 g sugar, egg yolk and the juice of the lemon. Add the frozen blueberries, pour everything into a fireproof glass bowl and let it get ice-cold in the refrigerator.
Beat the egg whites with the sugar until very stiff, place large dumplings on the yoghurt mixture with a tablespoon and bake in the preheated oven at not too high a temperature (120-150 °) until the tips of the egg whites are light brown.
Serve immediately!
The refined is the still cold inside and the warm outside.