Heat the milk: Set a Dutch oven or large heavy bottom non-reactive pot over medium heat. Add the milk. Let the milk slowly come up to 185°F. This should take about 20 to 25 minutes. Stir occasionally with a rubber spatula to prevent the milk from scalding on the bottom of the pot. When ready the milk should look a little foamy on top.
Add the lemon juice: Stir in the lemon juice and bring the milk up to 195°F. This should only take about 5 to 10 minutes. Once it reaches 195°F, shut off the burner. Pull a slotted spoon through the milk. It should have separated into curds and whey. The whey is the yellow liquid and the curds should be creamy, white clumps.
Spoon and strain: Line a fine mesh strainer with a double layer of cheesecloth. Set it over a bowl large enough to hold the whey. Spoon the curds in the lined strainer. Once the pot is easier to manage, pour all of the whey and remaining curds into the strainer. You will likely need to transfer the whey to another bowl or separate container so the ricotta can properly drain over the next couple of hours. You don’t want it sitting in the whey.
Cover and refrigerate: Once a good portion of the whey has drained away from the curds, fold any overhanging cheesecloth over the top of the ricotta and place it in the refrigerator to continue draining. The longer you let it drain the drier your ricotta will be. My sweet spot is about 4 hours, but I’ve also left it overnight. The ricotta will look crumbly. That’s OK. It’s much drier than what you would find in commercially made grocery store ricotta. Transfer to an airtight container and use within X days.
To make it creamy: If the ricotta feels too crumbly for your taste you can put it in your food processor and whip it up for a couple of minutes. If it still seems crumbly add 1 tablespoon of olive oil.
Whey: You can discard the whey or save it to replace the milk or water in bread recipes. You can also use whey to water acid-loving plants like azaleas and hydrangeas.
Salt or not to salt: I wait and salt my ricotta when I use it in different recipes. If I know I want to use it as a spread for toast I would put it into my food processor and add ½ teaspoon salt for every 2 cups of ricotta.