Pour the milk, cream and buttermilk into a large pot and place it over medium to medium-high heat.
Give it a stir, then let it slowly come up to a simmer (have patience) without disturbing it.
As soon as the milk just barely begins to bubble, turn off the heat. You don't want it to actually boil, but just barely start to gently simmer (190 degrees F if using a thermometer).
You will begin to see the milk solids start to separate and rise to the top. Again, don't stir. Set aside for at least 10 minutes to cool, undisturbed.
Line a colander or strainer with a few layers of cheesecloth *(see note).
Use a handheld strainer or large spoon to remove the curds from the liquid and place into the colander *(see note).
Allow the ricotta to drain to your desired thickness - the longer it goes, the thicker it will get *(see note).
Transfer to a container and refrigerate until ready to use. Homemade ricotta cheese will last I the refrigerator for about 5 days or up to 1 week.