Stuffed Portobello Mushrooms

Step 1
Preheat the oven to 350 degrees F (175 degrees C).

Step 2
Brush both sides of portobello mushrooms with Italian dressing. Arrange mushroom on a baking sheet, gill-sides up.

Step 3
Bake in the preheated oven until tender, about 12 minutes. Drain any juice that has accumulated in mushrooms.

Step 4
Beat egg, garlic, salt, and black pepper together in a large bowl.

Step 5
Stir spinach, pepperoni, Parmesan cheese, 3 tablespoons mozzarella cheese, and 3 tablespoons bread crumbs into eggs until evenly mixed.

Step 6
Divide spinach mixture over mushroom caps; sprinkle mushrooms with remaining 1 tablespoon mozzarella cheese and 1 tablespoon bread crumbs.

Step 7
Return mushrooms to the oven; bake until topping is golden brown and cheese is melted, about 10 minutes more.