Line a colander with cheesecloth and set over a large bowl.

Pour milk in a large nonreactive pot, clip a candy thermometer to the pot, and heat milk to 175°F.

Remove from heat.

Pour in the apple cider vinegar and stir. The milk will separate into curds and whey.

Let sit for about five minutes, then drain mixture into prepared colander.

Allow ricotta to drain for about 5 minutes, or longer if you prefer a firmer cheese.

Use immediately or store in an airtight container in the refrigerator. Store whey in refrigerator for another use.