Prepare croutons. Lay bread cubes on a baking sheet and spray lightly with cooking spray. Sprinkle with salt and pepper. Bake in 250 degree oven for about 20 minutes, until they are completely dry. This can be made ahead.
Preheat oven to 350. Lay chopped onions and tomatoes on a baking sheet and mix with 1/2 tablespoon of olive oil and sprinkling of salt and pepper. Roast about 45 minutes until tender and lightly browned. Let cool.
In a small bowl whisk the remaining 1 1/2 tablespoons oil with mayo, vinegar and mustard and salt and pepper to taste.
When ready to serve. Layer the lettuce, the tomatoes and onions and sprinkle a little bit of the dressing. Top with croutons and goat cheese and enjoy.