If you like onions, this is the way to go, even my un-houndly in-laws liked this dish.
Sweet large yellow onions
Bermuda (red) onions
Slice the stem end off the onions, then slice in half through the root, then peel back the outer "paper-like" layer of skin, then slice each half onion in to two quarters. Place the quartered onions in one layer on a baking sheet (I used a Calphalon non-stick jelly roll pan). Put a light coating of olive oil on the onions (I used a spray oil), then liberally sprinkle Kosher salt and fresh cracked black pepper on the oil coated onions, turn the onions over to expose the side that was not coated, and repeat.
Roast in the oven until done, half-way through the roasting, turn the onions over to expose another side to the bottom of the roasting pan. Since I was roasting these while warming other food, I set the oven temp to 375, total roasting time was about 60 minutes. I have roasted these as high as 400, and actually prefer the higher temperature, don't roast over 400 unless you want to see your roasting pan warp.
It might also help to put a thin layer of olive oil in the bottom of the roasting pan. The cut side of the onions that are in contact with the bottom of the pan will carmelize first, that is why you need to turn them at least once, to carmelize another side.
The onions come out tender and sweet.