Peel the onions and cut them into thin slices. Transfer to the bowl.
Add the brown sugar, balsamic vinegar, and laurel in a bowl with onion slices. Mix all well and then let it macerate for 3 hours.
After time has elapsed, pour the mixture into a pan and bring it to a boil, mixing occasionally. Let it cook for 45 minutes.
The onion jam is ready when the liquid has caramelized and we have a nice thick mixture.
Fill the jar with the onion jam. Serve the onion jam on bread or with cheese.
