In a medium pot, bring the cream, milk, and buttermilk to a gentle simmer over medium heat. Simmer gently for a few minutes until the milk solids rise to the surface and form what looks like a raft. Shut off the heat and allow the milk to rest and cool gently on the stove, 15 to 20 minutes.
Line a strainer with a few layers of cheesecloth. Use a large spoon to scoop the solids from the surface into the strainer. Pour the liquid gently over the solids in the strainer, allowing the liquid to flow through the strainer and trapping the solids in the cheesecloth. The liquid is the whey and can be used to thicken soups or as a substitute for water in bread dough, among other things. Refrigerate for a few hours to allow all of the liquid to drain out and the ricotta to firm up slightly. Use the ricotta as desired.