This is going to sound like a ridiculous amount of onions, but they keep in the fridge for 2 weeks and in the freezer for 6 months. You may as well make a crapton and put them on everything.
4 pounds Vidalia onions
3 tablespoons butter
1 tablespoon balsamic vinegar
Peel and slice the onions in 1⁄4″ slices. I like to use a mandolin slicer like this one:
Thinly slice the butter. Place the onions in the slow cooker and sprinkle the butter over the top of the onions and drizzle with balsamic vinegar. The slow cooker will look too full but the onions will reduce in no time. Cover and cook on low for 10 hours. If after 10 hours the onions are too wet, turn the slow cooker up to high and cook uncovered for 30 minutes or until the liquid evaporates.