Combine parsley, thyme, rosemary, and garlic. Set aside.
Heat oil in a large nonstick skillet over medium-high heat.
Add mushrooms, leek, 1/4 teaspoon salt, and 1/8 teaspoon black pepper; saut 10 minutes or until liquid evaporates and mushrooms are lightly browned.
Add half of parsley mixture; cook 1 minute, stirring constantly. Stir in bell peppers.
Remove from heat; cool slightly.
Combine remaining 1/4 teaspoon salt, remaining 1/8 teaspoon black pepper, remaining parsley mixture, milk, egg substitute, and 3/4 cup cheese in a large bowl, stirring with a whisk. Stir in mushroom mixture.
Add bread; stir gently to combine.
Let stand 10 minutes. Spoon into a 2-quart baking dish coated with cooking spray.
Sprinkle with remaining 1/2 cup cheese.
Bake at 350 for 45 minutes or until pudding is set and lightly browned.