On the stovetop, bring the milk to 180°F (82°C) over medium heat while whisking occasionally. Use a candy thermometer to ensure that you are getting the right temperature.
Once it reaches 180°F (82°C), take the milk off of the heat and stir in the vinegar right away. You should begin to see the yellowish whey separating from the curds immediately.
Allow the curds and whey to cool at room temperature for approximately 30 minutes.
Line a colander with a double-layer of cheesecloth. Put the colander in the sink or a large bowl. Pour the curds and whey into the lined colander. Let drain for 5 minutes. The curds will stay in the cloth while the whey will drain away. (The whey can be discarded or saved to be used in another recipe.)
Gather up the edges of the cheesecloth so that the curds are collected into a tight ball. With clean hands, squeeze the ball gently over the sink to release more whey. If you are concerned about a vinegar taste remaining, you can run the ball under gently running water and squeeze again, if desired.
Unwrap the cheesecloth. You can use the cheese before you as a ricotta substitute in your recipes. If you want cottage cheese instead, continue on...
Put the cheese ball in a bowl and gently break up the curds with a fork. Stir in the heavy cream. You will find that the curds readily absorb the cream, so the finished cottage cheese does not contain much liquid.
If you used 2% milk, this recipe makes approximately three cups of loosely packed cottage cheese. Refrigerate and enjoy!