In a large mixing bowl, combine ground beef or turkey, breadcrumbs, Parmesan cheese, parsley, egg, minced garlic, onion powder, salt, and pepper. Mix until just combined.
Form the mixture into 1-inch meatballs and place them on a baking sheet lined with parchment paper.
Bake the meatballs in the preheated oven for about 20 minutes, or until they are browned and cooked through.
In a large mixing bowl, toss the cubed French bread with half of the marinara sauce, dried Italian herbs, chopped bell pepper, and sliced black olives.
In a 9x13-inch casserole dish, spread the bread mixture evenly at the bottom. Top with baked meatballs, the remaining marinara sauce, and shredded mozzarella cheese. Sprinkle sliced pepperoni over the top.
Cover the casserole with aluminum foil and bake for 20 minutes. Then, remove the foil and bake for an additional 10-15 minutes, or until the cheese is bubbly and golden brown.
Once done, let the casserole cool for a few minutes. Sprinkle with chopped green onions before serving.
Serve warm and enjoy the cheesy, saucy goodness!
Notes
Feel free to add more vegetables or adjust the spices to your taste.