Preheat your oven to 375°F (190°C).
Cut each zucchini in half lengthwise and scoop out the center using a spoon.
In a skillet, heat some oil over medium heat.
Add the diced onion and garlic, sautéing until softened.
Add the ground turkey or beef, cooking until browned.
Stir in the marinara sauce and Italian seasoning, mixing well.
Season with salt and pepper to taste.
Fill each zucchini half with the meat mixture.
Top with shredded mozzarella cheese.
Place the zucchini boats on a baking sheet and bake for 25-30 minutes until the zucchini is tender.