Preheat oven to 350°F. Remove mushroom stems and use a spoon to scoop out dark mushroom gills, being careful not to break mushroom caps. Place mushrooms cup-side-up on a rimmed baking sheet and set aside

Heat 1 tablespoon olive oil in a large skillet over medium heat. Add bread crumbs and cook, stirring frequently until golden-brown, about 10 minutes. Transfer to a bowl to cool and wipe out skillet. Add remaining olive oil and onion, red pepper, green pepper, salt and Italian seasoning. Cook until vegetables have softened, about 7 minutes. Transfer mixture to a large bowl and let cool 5 minutes. Add mozzarella cheese, ham and parsley.Stir to combine.

Generously stuff each mushroom with filling mixture. Top with bread crumbs and bake for 25 minutes, or until mushrooms are tender. Garnish with fresh parsley.