A blintz is a very thin pancake that's rolled around a filling and either baked or fried. Sweet blintzes are usually filled with cheese.
Blintzes can be sweet or savory, stuffed with sugary ricotta cheese and baked, or filled with ground meat or potato and fried. Every blintz starts with a blini, the crepe-like pancake that is wrapped around a filling before being cooked. Sometimes they're topped with a dollop of sour cream. Blintz, from the Yiddish blintze, stems from the Russian blinyets, "little pancake."