Preheat oven to 325 degrees.
Brown sausage in a large skillet and drain most of the fat. Add vegetables, garlic, and seasoning and cook five minutes. Set aside.
Mix together eggs, half and half, and dry mustard in a mixing bowl. Cut the bread (or croissants) into small cubes. Fold the bread, cheeses and sausage mixture into the eggs. Mix well and place in a buttered two-quart baking dish.
Bake for 40-50 minutes. Allow to rest for 15 minutes before serving. Yield: eight servings