4 large portobello mushroom caps
3/4 cup mozzarella cheese – 1/2 cup for the filling and 1/4 cup for topping the mushrooms
1/4 cup plus 2 tablespoons marsala wine, divided
3 tbsp. grated parmesan cheese
5 cups chopped fresh spinach
1 lb. ground chicken
1/2 tsp. ground pepper
1 tsp. salt
2 garlic cloves, minced
1/2 cup diced onion
1 tbsp. olive oil