What Can I Substitute for Quark? Quark is something of a cross between yogurt, cottage cheese and ricotta, and while obviously not exactly the same, you can substitute any one of these. If using yogurt, use Greek yogurt and strain it in a cheesecloth to thicken it (you'll want 500 grams of strained, thickened yogurt). If using cottage cheese, first blend it until it's smooth.