Preheat your oven to 400°F (200°C).
In a mixing bowl, combine the lean ground beef, egg, breadcrumbs, Parmesan, garlic powder, and a pinch of salt. Mix until just combined to avoid overworking the meat.
Form the mixture into meatballs, roughly 1-inch in diameter.
Place the meatballs on a baking sheet lined with parchment paper and bake for 15-18 minutes until cooked through.
While the meatballs bake, slice the zucchini into rounds or half-moons. Toss in olive oil and season lightly with salt and garlic powder.
Spread the zucchini on another baking sheet and roast in the oven for about 10-12 minutes until tender and lightly browned.
Warm the marinara sauce in a small pot over medium heat until heated through.
Plate the roasted zucchini, top with the beef meatballs, and drizzle the marinara sauce over the dish.
Serve immediately and enjoy your nutrient-packed, flavorful meal.