This cheesy brunch entree with fresh onions, mushrooms and tomatoes and savory sausage will smell so good as it bakes, they'll be at the table before the first cup of coffee.
French onion soup gets its full-bodied taste from slow-cooked, caramelized onions. Here, we call for three types of onions for rich, balanced flavor, but the recipe will work with any combination or just one variety.