Using an apple corer cut out the center of the tomatoes without piercing the bottom- you might need to gently use a paring knife to help remove the center. Squeeze out the seeds and place tomatoes cut side down on a baking sheet coated in olive oil.
In a bowl mix together the diced provolone, parmesan cheese and ricotta cheeses with the green sauce and the egg. Gradually mix in about a 1/4 cup of plain breadcrumbs. Add more breadcrumbs a tablespoon at a time if the mixture seems loose.
Turn the tomatoes over and fill with mixture using a very small spoon (like an espresso spoon). Using your hands, rub the outside of the tomatoes with olive oil before baking.
Bake the tomatoes in the oven for 25 minutes (or until fully cooked); remove pan from oven and lay the remaining provolone slices over the tomatoes and place under the broiler on low until melted.
Serve warm and enjoy!
Swap out provolone for a milder cheese like mozzarella or fontina.