Make cheese!
Start with 5 litres, heat the milk slowly, with a tablspoon of salt, until it is hot, but not yet simmering. Add the juice of a lemon, or two, and watch the curds seperate.
Drain into a colander lined with a double layer of muslin. Leave it to sit for a while, and you should then have a mass of curds ready to drain properly. At this stage you can gather up the ends of the muslin, and shape the curds into a compact shape. Tie the ends up, and suspend your cheese over a bowl, or the sink, so it can quietly drip.
The resulting curd cheese is very useful, on it's own, or in cooking.
Be aware that if you heat the curds too long, the resulting texture will change. It will become oddly springy. Not good, unless you want to aim for something half way between ricotta and mozzarella. If you keep things quick, and the temperatures modest, then you should have a light and creamy sort of fresh cheese.