Place the buttermilk cartons into a large, deep pot. Add hot water up to the part where the sides of cartons start to fold.
Bring to a boil, reduce the heat and simmer (gently boil, bubble) for 45 minutes.
Remove pot with buttermilk cartons from the heat and let cool down. Gently remove the cartons from the water and cool completely in the refrigerator, preferably overnight.
Place a fine-mesh sieve over a pot to catch the whey, if desired. Open the cartons by unfolding the top (or cut with scissors) and slowly empty over the sieve. Let drain for a few minutes. For dryer cheese, drain longer.
Transfer the farmer's cheese into an air-tight container. Store in a refrigerator for up to two weeks.
If you have an extra deep pot, you can use larger buttermilk cartons. Just make sure the water level is up to the folding point.
5 simple ways of using the farmer's cheese, just to get you inspired:
Drizzle with honey and top with fruit for a delicious snack.
Mix in sliced green onions, olive oil, salt, and pepper. Serve with crackers or crusty bread for an appetizer or as a country-style salad (substitute the cottage cheese).
Use as the filling for lasagna, pasta shells, ravioli, or pierogies.
Blend with yogurt, sour cream, or mayonnaise as a base for a dip.
Use it as a spread for sandwiches, wraps, and pitas.