If you can't find quark, strained Greek yogurt like Fage is a great alternative. To get the same amount as 750 g (3 cups) of quark, you'll need about 1 kg (4 cups) of Greek yogurt since some weight is lost when draining. How to Strain Greek Yogurt: Place 1 kg (4 cups) of Greek yogurt in a fine mesh sieve or cheesecloth-lined colander over a bowl. Let it drain in the fridge for a few hours or overnight to remove excess liquid. After draining, you’ll have a thick, creamy yogurt similar to quark, perfect for the cheesecake filling.