Preheat the oven to 400°F (200°C). Place the halved spaghetti squash cut-side down on a baking sheet and roast for 30-35 minutes until tender.

Once cooked, let it cool for a few minutes, then use a fork to scrape the flesh into spaghetti-like strands.

In a skillet, heat olive oil over medium heat. Add minced garlic and sauté for 1 minute until fragrant.

Add sliced mushrooms and cook for 5-7 minutes until softened. Stir in chopped spinach and cook until wilted.

In a mixing bowl, combine the sautéed vegetables with cream cheese, Parmesan cheese, salt, and pepper. Mix until well combined.

Fill each spaghetti squash half with the creamy spinach and mushroom mixture, pressing down gently to pack it in.

Sprinkle additional Parmesan cheese on top of the stuffed squash.

Return the stuffed squash to the oven and bake for an additional 10-15 minutes until heated through and the cheese is bubbly.

Remove from the oven, let cool slightly, and serve warm.