Heat milk in a heavy-bottomed saucepan over low heat, stirring regularly, to 175 degrees F (79 degrees C). Pour buttermilk and lemon juice into milk and remove from heat. Stir gently with a wooden spoon; the curds and whey will begin to separate. If mixture does not curdle, add another teaspoon of lemon juice. Let milk mixture sit for 10 minutes.
Place a colander over a stockpot and line the colander with 4 layers of cheesecloth. Ladle cheese curds into prepared colander. Let drain for 5 minutes.
Gather the cheesecloth and tie at the top with twine or string. Tie cheesecloth bag to a wooden spoon and hang it over the stockpot. Let drain for 30 minutes.
Cut off tied top of cheesecloth. Unwrap the drained cheese and turn out into a bowl. Mix salt into cheese with a wooden spoon. Transfer cheese to a ramekin, cover ramekin with plastic wrap, and refrigerate 8 hours to overnight.