In my infinite spare time, I have been exploring cheese making. I have several fresh cheeses comfortably under my belt, the easiest of these is ricotta. You might be thinking to yourself, "That's silly, ricotta is so expensive in the store that it can't possibly be easy to make at home." This, however, is exactly what they want you to think so you buy their product, because if you knew how easy it actually is to make, you wouldn't buy their product.
There are lots of recipes online for homemade ricotta, but I find that it's actually more of a technique than it is a recipe. And it's really as simple as this...
In a saucepan, bring a pretty good amount of whole milk slowly up to 185º, stirring often to prevent scorching (but it's okay if it does start to stick to the bottom of the pot, just don't scrape it off into the milk). Have a pretty good amount of fresh lemon juice on hand. Once the milk is up to temp, remove the pot from the heat and stir in the lemon juice. As you stir the milk will curdle. Add enough lemon juice until you get a clear separation between the curds and whey. Let the curds sit for about 10 minutes, then ladle them into a colander lined with double layer of cheesecloth (I usually just pour the whole damn thing through the cheesecloth and let it do the work for me, rather than mess with a ladle). When most of the whey has drained out of the curds, tie up the ends of the cheesecloth into a bag and hang the curds over a bowl or sink until they don't drip anymore and are pretty dry and crumbly.
If you want, you can dump the drained curds into a bowl and toss with some salt to taste before containerizing it for later use. The ricotta will be good for up a week, well sealed.
Why no set amount of acid? Because the amount of lemon juice needed will depend on many factors: how old the milk is, how quickly it's brought to temp, how old the lemons are, how acidic the lemons are. I usually make ricotta from about a gallon and a half of milk and it takes a cup or more of lemon juice to get a clear separation of whey. These same factors will also affect the size of the curds you get. Sometimes I get nice big clumps of curds, other times I get small bits and flakes. The end result is all the same however.
Homemade ricotta is going to be drier than what you get in the store, but far cheaper and more tasty. You might have to add a little cream to your ricotta to get the same consistency as store-bought for use in some recipes, but if you're making gnocchi or ravioli filling or something like that, the drier consistency is better anyway.
"But isn't it going to taste like lemon?" A bit. You can use a solution of citric acid in water to curdle the milk, though I have not tried this to know what sort of proportion to use. But, come on, you'd be very hard pressed to find a recipe that couldn't benefit from a little bit of lemon flavor.
"Oy! Now I have all this stupid whey!" Use it in pancake batter. Use it to feed your sourdough starter. Use it to make dutch babies. You could probably add it to smoothies, and probably find other uses for it online. Water your garden? Who knows? Don't use it for pate a choux though, it doesn't work.