This version is easier (not so much stirring) and lighter (not so much oil) than the stove top version. I like to slice my onions using a food processor to make things even easier.
Preheat the oven to 450 degrees F with cast iron skillets inside.
Place the onions in a large bowl. Drizzle the olive oil over them and season them with salt and pepper. Toss them well.
Divide evenly between pans. Shake to distribute evenly in each pan. Roast for 8 minutes and stir. Roast for 8 to 10 more minutes until the onions are cooked through and caramelized (soft and lightly browned).
Make sure to keep an eye on things towards the end. Make sure not to overcook because you do not want crispy onions.
Find it online: http://shiftycrafty.com/caramelize-onions-oven/