This kit is pretty simple--comes with muslin (better than cheesecloth because it's a finer weave), rennet, citric acid, cheese salt, a thermometer and an instruction book. Sure you could probably find all those things separately for less money, but would you? I've had this cute kit for at least a couple of years and it still works fine. (I keep the rennet in the freezer.)
So to make ricotta, you heat a gallon of milk up to 195˚F while stirring it pretty much constantly. Also, you add citric acid. This serves to break up the protein from the liquid (which becomes whey). The protein gets strained out as cheese, and you have a whole mess of whey left over. Apparently you can get the same effect from lemon juice--see this Smitten Kitchen post for a description (and pretty pictures). I also used Smitten Kitchen's idea of adding some heavy cream for texture. I had half a pint kicking around. From... making ice cream.
Heating a gallon of milk slowly so it doesn't burn takes forever. Or put another way, at least half an episode of Sherlock. Then you turn off the heat and let it sit, then ladle the curds into the cheesecloth to strain.
Here is my straining system. It's hard to see, but I rigged up a figure-eight of two rubber bands to hold the handle and end of the strainer firm so it wouldn't slide back down into the bowl. I left it overnight to strain. (Refrigerated, of course.)
Here's how it looked inside the cheesecloth. It's a lot more compact and drier than commercial ricotta. It's more cheese-like. However it crumbles up fine and tastes pretty delicious. Like the essence of milk and cream, distilled and cheesified.
The first thing I made with my homemade ricotta was a batch of canneloni, our family's meaty-cheesy-tomatoey alternative to lasagna. Delicious. But I still had half the ricotta left. For this I wanted to try some sweet application. Crepes maybe? Then I saw an episode of No Reservations where Anthony Bourdain travels to Sicily. Guess what they invented there that uses sweetened ricotta?
I have never seen The Godfather so don't worry about mob-ilicious cannoli quotes. All I want is to use this lovely ricotta before it goes bad. Since it was kind of dry, I smashed it all up and moistened with a bit of milk. Then I sprinkled on white sugar and added a glug of vanilla. Stirred it all together and tasted--great! I stuffed it into one of my super-handy disposable piping bags and stashed it in the fridge. I bought 6 cannoli shells at the super market. I dug out some OLD cherries from the back of the fridge. Now I can pipe my own cannoli any time, man.