Rinse and dry mushrooms, remove the stem from the cap. Chop stems and reserve for later.
In a large skillet heat 1 tbsp of olive oil over medium heat. Add garlic and onion and saute until onions are translucent. Stirring constantly.
Add mushroom stems and saute for 2 minutes. Add sausage and spinach. Cook for 1 minute. Add bread crumbs (reserving some for topping). Cook for 2 minutes.
Remove from heat and add basil, parsley, Parmesan, mozzarella, salt and pepper. Stir to combine.
Coat each mushroom cap with olive oil and season with salt and pepper. Put about 2 tbsp of the filling in each mushroom cap.
Prepare a foil lined, oil coated, baking sheet. Spread out rosemary and thyme on top of the oil coated baking sheet. Place stuffed mushrooms on top of rosemary and thyme. Sprinkle with remaining bread crumbs.
Broil in oven on lowest rack position for 10 minutes or until mushrooms are tender and tops are golden brown.
