1.  Preheat oven to 425 degrees and lightly spray a large rimmed cookie sheet with nonstick spray.  Remove the stems from the mushrooms and use a spoon to remove the dark gills on the inside of mushroom.  Lay them top side down on the sheet.  Combine the olive oil and garlic, then spread it evenly inside each of the mushrooms.  Generously salt and pepper each mushroom and place in the oven for 10 minutes.
2.  In a medium bowl, mix together the ricotta, egg, parmesan, 3/4 of the mozzarella, spinach, italian seasoning, salt and pepper.  Remove the roasted mushrooms from the oven and use a paper towel to absorb any pooled liquid inside the mushrooms.  Generously fill each mushroom with the cheese mixture, spoon on a couple tablespoons of pasta sauce on each then top with the remaining mozzarella cheese.  Bake for another 10 minutes.  Serve with additional pasta sauce on the side.