Add milk and cream to a sauce pan. Bring just up to a simmer (not over) over medium high heat.
Remove from heat, stir in vinegar and salt. Let sit for 5 minutes for curds to form, you should see them lumping up on the back of the spoon and in the mixture.
Pour mixture through a couple layers of cheese cloth (or 3-4 layers for a looser, wetter ricotta), or one layer of muslin cloth. Either tie the bag-like shape together and hang it over something to catch the draining liquid, or fix it over a large mouth jar with a rubber band.
Once the ricotta is the consistency you like, remove it from where it's hanging or fastened to and give it a final squeeze.
Dump it from the cloth into a bowl or container. You can use it as is, in various recipes, or add herbs to it for a nice spread.