Preheat the oven to 350°F (175°C).
Cook the orzo according to package instructions and set aside.
In a bowl, mix ground meat, breadcrumbs, egg, Parmesan, salt, pepper, and Italian seasoning.
Form the mixture into meatballs, about 1 inch in diameter, and arrange them in a baking dish.
Pour marinara sauce over the meatballs and sprinkle chopped spinach on top.
Mix in the cooked orzo until everything is well coated.
Sprinkle shredded mozzarella cheese on top.
Cover with aluminum foil and bake for 25 minutes, then remove the foil and bake for an additional 10-15 minutes.
Allow the bake to cool for 5-10 minutes before serving.