Preheat oven to 375°℉
Line a sheet pan with non-stick aluminum foil, or regular foil and spray with vegetable cooking spray.
Peel and slice 2 whole Spanish onions and place on sheet pan, spreading out so the onions are evenly distributed; drizzle with olive oil and season with kosher salt and black pepper to taste.
Slice 1/2 loaf baguette half length wise and then cube into 1/2 - 1 inch pieces.
Place marinated chicken, skin side up, on top of the onions
Top with cubes of bread, tucking the bread around and under the chicken
Bake in a pre heated oven for 30-45 minutes, or until the chicken is nicely browned and the onions and bread toasted.