Step 1: Preheat the Oven

1. Preheat your oven to 400°F (200°C).

Step 2: Prepare the Spaghetti Squash

1. Carefully cut the spaghetti squash in half lengthwise and scoop out the seeds.
2. Brush the insides with olive oil and season with salt and pepper. Place the squash cut-side down on a baking sheet lined with parchment paper.
3. Roast in the preheated oven for 30–40 minutes, or until the flesh is tender and easily shredded with a fork.

Step 3: Prepare the Filling

1. In a large skillet over medium heat, add olive oil and sauté the onion and garlic until fragrant. Add the bell pepper and zucchini, cooking until softened.
2. Stir in the cooked ground turkey or chicken, Italian seasoning, salt, and pepper. Mix well and cook for an additional 2–3 minutes.
3. Remove from heat and stir in the marinara sauce until well combined.

Step 4: Stuff the Squash

1. Once the spaghetti squash is done roasting, use a fork to shred the flesh into spaghetti-like strands.
2. In a large bowl, combine the shredded squash with the filling mixture, mixing well.
3. Spoon the mixture back into the roasted spaghetti squash halves and top with shredded mozzarella cheese.

Step 5: Bake Again

1. Return the stuffed squash to the oven and bake for an additional 10–15 minutes, or until the cheese is melted and bubbly.

Step 6: Serve

1. Remove from the oven, let cool slightly, garnish with fresh basil if desired, and serve with extra marinara sauce on the side.