Delicious doughnuts made with a cheese-enriched dough. Tvorog (Russian cottage cheese) is traditionally used for this recipe, but it works very well with ricotta, too.
The oil should be hot but not smoking. It is ready for frying if you see little air bubbles around a wooden spoon placed in the oil.
If you want your doughnuts to have a smoother surface, press the cheese through a sieve before adding to the mixture.