Now you can do a heap of caramelized onions and not have to watch them incase they burn. Do far more than you need, and freeze them in small containers for up to 3 months. Perfect!

Makes several cups

5 large yellow onions
3 tbsp extra virgin olive oil or melted butter, or a mixture of the two
1/2 tsp salt
Optional: 1/2 to 1 tsp chopped fresh thyme

You will need a 4 to 6 qt slow cooker

Thinly slice all the onions;  Peel and thinly slice all of the onions into half moons. Transfer all the onions to the slow cooker. The slow cooker should be 1/2 to 3/4 full.

Toss the onions with the olive oil;  Drizzle the olive oil/melted butter, the salt and the fresh thyme, if using, over the top of the onions. Toss evenly to coat all the onions with a thin glaze of oil

Cook for 10 hours on LOW; Cover the slow cooker and cook for 10 hours on LOW. If you’re around while the onions are cooking, stir them occasionally – this will help them cook more evenly, but isn’t strictly necessary.
After 10 hours, the onions will be golden-brown and soft and they will have released a lot of liquid. If you like them as they are now, stop cooking and pack them up.

Optional, and worth it – cook for an additional 3 to 5 hours with the lid ajar; If you’d like jammier, more concentrated onions with a deep color, continue cooking for another 3 to 5 hours on LOW. Leave the lid ajar so the liquid can evaporate.
Check every hour and stop the cooking whenever the onions reach your desired doneness and taste good to you