Heat oil in a large nonstick skillet over medium-high heat. Add onion, potato, and bell pepper; sauté 4 minutes or until tender. Stir in tomatoes; sauté 2 minutes. Stir in 1/2 teaspoon salt. Combine onion mixture and bread.
Place half of bread mixture into a 13 x 9-inch baking dish coated with cooking spray. Sprinkle with half of Brie. Top with remaining bread mixture and remaining Brie.
Place egg substitute and eggs in a medium bowl. Add remaining 1/2 teaspoon salt, herbes de Provence, and pepper. Add milk, stirring with a whisk until well blended. Pour egg mixture over bread mixture. Let stand 30 minutes.
Preheat oven to 350°.
Bake at 350° for 50 minutes or until set. Sprinkle with parsley. Serve immediately.