Preheat your oven to 375 degrees Fahrenheit.
Trim the ends off each zucchini and grate them into a large bowl using a cheese grater.
Place the shredded zucchini into a colander in the sink and sprinkle with salt. Let it sit for 20 minutes to draw out excess moisture.
Wrap the zucchini in a dish towel and squeeze out as much liquid as possible, then transfer it to a large mixing bowl.
Add the egg, ricotta cheese, panko breadcrumbs, Italian seasoning, chopped basil, chopped parsley, black pepper, olive oil, diced onion, and minced garlic to the zucchini. Stir until all ingredients are thoroughly combined.
Shape the mixture into golf ball-sized meatballs and arrange them on a rimmed baking sheet. Bake for 35-40 minutes, turning them halfway through cooking.
While the meatballs bake, prepare the marinara sauce. Heat the olive oil in a large skillet over medium-high heat.
Add the garlic and sauté until golden, taking care not to burn it.
Stir in the crushed tomatoes, salt, black pepper, oregano, and bay leaf. Reduce the heat to low, cover, and simmer for 15-20 minutes.
Remove the bay leaf and stir in the fresh basil.
Add the baked meatballs to the marinara sauce, serve, and enjoy!