Line a colander with a clean tea towel and place it over a large bowl (to catch the whey). Pour the curds and whey into the colander and let the curds strain for at least an hour. At an hour, you’ll have a tender, spreadable ricotta. At two hours, it will be spreadable but a bit firmer, almost like cream cheese. (It will firm as it cools, so do not judge its final texture by what you have in your towel.)