Place the chicken in a bowl and season it with the grill seasoning. Add the egg, half of the grated cheese, bread crumbs, parsley, and a big drizzle of the olive oil.
Combine the mixture and form 12 large meatballs, placing them on a baking sheet. Squish the balls to flatten them a bit - like mini oval meatloaves. Be careful not to form the balls wider than your bread. The flattened balls will stay put on your sub - no roll-aways! Bake the meatballs for 15 minutes, or until golden and firm. Switch the broiler on.
While the chicken balls bake, heat a medium skillet over medium heat. Add the 3 Tablespoons of olive oil and the garlic and cook them for 5 minutes. Discard the garlic, add the red pepper flakes and the tomatoes, and stir in the chicken stock. Season the sauce with salt and pepper and simmer for 10 minutes. Adjust the seasonings and stir in the basil.
Use a thin spatula to loosen the chicken balls from the baking sheet and add them to the sauce, turning the meatballs to coat.
Cut the sub rolls, making the bottom a little deeper than the top. Hollow out a little of the bread and lightly toast the sub rolls under the broiler. Fill the bottoms of the breads with the sauced meatballs. Combine the provolone and the remaining parmesan cheese. Cover the meatballs with cheese and return to the broiler to melt the cheese until it's golden. Set the roll tops in place. Pour any leftover sauce into a bowl and serve at the table for dipping.