Here is a simple recipe for making a Ricotta style cheese with just some milk and vinegar, made in minutes.
Simple Ricotta Style cheese
2 litres milk (can be any type of milk, even UHT) 90ml white vinegar Sea salt, as required
Heat milk in a large saucepan to 90°C uncovered (do not allow to boil), stirring occasionally with a large metal spoon.
Remove saucepan from the heat, add vinegar and stir briefly. Curds should start to form instantly. Set aside for 10 minutes, covered.
Lift the ricotta from the whey using a slotted spoon and fill a small colander. Sprinkle ricotta curds with salt as you are filling up the colander. The ricotta can be eaten immediately or left to drain for a few hours (or overnight) for a firmer texture. Turn out ricotta and store in fridge for up to 4 days.