I got this idea from my mother, who regularly makes these onions in her crockpot, then enjoys them on cold sandwiches or with her dinner. She likes to use whole onions. I decided to slice this batch to make them easier to serve. Here's what I used:
Start with about 3 pounds of sweet onions. These are from Central Market and are called Texas Sweet, very similar to Vidalias.
I put about 1 1/2 sticks of unsalted butter in the bottom of my big crock pot and set the temp to low while I sliced up the onions. I had to work fast - those onions were powerful! I always end up looking like something out of a horror flick with red eyes and tears streaming down my cheeks.
This time I sprinkled about a tablespoon of brown sugar over them, but you could skip this step. Especially if you are using a variety of sweet onion. I covered them, and off the boys and I went to do errands and pool all day. These spent about 9 1/2 hours on low.
Halfway through the cooking time I gave them a stir. The onion aroma filled the kitchen and people came running to see what was for dinner...sorry, no onions tonight Before bedtime they had turned a nice light caramel color and I ladled them into jars to cool and store in the fridge.
When you slice them its hard to tell this is a jar of onion. But it will make the most amazing thing to add to a burger, cold from the fridge. It makes a great leftover roast sammie, is good in an omelette or quesadilla, and a spoonful of it stirred into beans is great! The cooking time is an estimate - If you want them darker, cook them a little longer; lighter, cook them less. Eyeball them for color and texture and when they look like what you intend to use them for, stop cooking. You can't really go wrong if you're an onion lover. Try 'em and tell me what you think!