Start by preheating the oven to 350F. Line a baking tray with parchment paper.
Combine in a large bowl, the ground turkey, egg, oregano, salt, panko crumbs, and parmesan. Stir to combine.
1 pound Ground Turkey, 1 large Egg, ½ cup Panko Crumbs, ¼ cup Parmesan Cheese, 1 teaspoon Salt, 1 teaspoon Dry Oregano
Chop the spinach very finely and stir it into the turkey mixture until well incorporated.
2 ounces Baby Spinach
Shape the turkey florentine mixture into 20 equal meatballs. Place them evenly spaced on the prepared baking sheet. Bake for 15 minutes in the 350F oven, or until the internal temperature reaches 165F.
While the meatballs are baking, place a large saucepan on medium heat. Drizzle a little olive oil in the pan and add to it the minced garlic and chopped onion. Cook until onions are translucent. Pour the marinara into the pan.
1 tablespoon Olive Oil, 3 cloves Garlic, 1 medium Yellow Onion, 2 cups Marinara Sauce
Add the cooked meatballs to the pan with the sauce. Stir to coat them in the sauce and bring to a simmer. Cook on low for 3-5 minutes.
Remove the parchment from the baking pan and replace it with aluminum foil. Fill the bread rolls with 4 meatballs in each and place on the sheet pan. Spoon the sauce over the meatballs and cover with the slices of provolone.
5 pieces Hot Dog Rolls, 5 slices Provolone Cheese
Place the sheet pan of Turkey Florentine Meatball Subs under the broiler of your oven, just until the cheese has melted. Remove from the oven and serve.