Although onions aren't often the star in a recipe, they provide an essential layer of flavor in almost every type of cuisine. Cooking them on the stovetop requires that you hover over them until they are done. Cook them in the oven with less fuss.
The length of time you cook your onions in the oven will vary according to the results you want. For the texture of fried onions, roast them with a little oil for about 15 minutes at 425 degrees Fahrenheit. Caramelized onions take between 2 and 2 1/2 hours. Put your onions and a little oil in a lidded Dutch oven or casserole in an oven preheated to 400 F. Take them out of the oven and stir them every 15 minutes until darkened in color, and are sweet and slightly sticky.