Ryazhanka

ryazhenka, riazhanka, ряжанка

Ryazhenka, or ryazhanka , is a traditional fermented milk product in Belarus, Russia, and Ukraine. It is made from baked milk by lactic acid fermentation. Russian and Soviet sources call it "Little Russian ryazhenka", "Ukrainian ryazhenka", or "Ukrainian soured milk" (украинская простокваша, ukrainskaya prostokvasha) and attribute its origin to Ukrainian cuisine. The name is cognate with the Ukrainian "пряжений" as in "пряжене молоко" (pryazhene moloko, "baked milk").

Source: Wikipedia