Make Ahead Caramelized Onions - cooking recipe

Ingredients

5 lbs onions, cut into 1/4 to 1/2 inch slices
1/2 cup unsalted butter
2 teaspoons salt

Preparation

Put the butter in a 4 quart or larger slow cooker insert.
Separate the onion slices into rings and add them to the slow cooker, lightly packing them down.
Sprinkle the salt over and cover with the lid, (the cooker will be quite full).
Cook on high until the onions are very soft and a deep caramel color, about 10 to 12 hours, stirring once or twice.