1 gallon of milk
3/4 cup white vinegar
1 1/2 tsp. Kosher salt
1/2-3/4 cup cream
Colander
Tea towel
This is a good way to deal with milk that has expired or just started to go sour, but hasn't actually spoiled yet.
Pour the milk into a large saucepan, add the salt, and place over medium low heat. Warm to 130 degrees F. Stir periodically.
Turn off the heat and stir in the vinegar. Stir slowly as it begins to separate.
Allow to sit for 30 minutes.
If it is completely separated, skip to straining. If it isn't completely separated, follow the next step. You will know it is completely separated when the liquid looks yellow and thin.

If there are any pieces large enough to remove, spoon them out into your towel lined strainer.
Heat the remaining liquid up to 180 degrees. Turn off the heat, add another 1/4 cup of vinegar and let sit another 30 minutes.
Straining:
Pour the mixture into the tea towel lined strainer and allow to drain until the liquid appears to be mostly gone. 
Using the towel, squeeze as much liquid out of the curd as you can and transfer it to a bowl.
Break it into bite sized pieces and put in an airtight container in the fridge for up to a week.
Add the cream when served or used.
Occasionally you will end up with smaller curds, similar to ricotta.
*You can use the sous vide method as described here: Ricotta Cheese