Preheat your oven to 400°F (200°C).

Cut the spaghetti squash in half lengthwise, scoop out the seeds, drizzle the inside with olive oil, and sprinkle with salt and pepper.

Place the squash cut side down on a baking sheet lined with parchment paper and roast for 30-35 minutes until fork-tender.

While the squash is roasting, heat olive oil in a skillet over medium heat.

Add the diced mushrooms and cook for 5-7 minutes until browned.

Include the minced garlic and sauté for another minute until fragrant.

Add the chopped spinach and cook until wilted.

In a bowl, combine the sautéed vegetables with cream cheese, Parmesan cheese, salt, pepper, Italian seasoning, and optional red pepper flakes. Mix thoroughly until combined.

Once the squash is done roasting, fluff the flesh slightly with a fork. Turn the halves cut side up and fill each half generously with the creamy filling.

Return the stuffed spaghetti squash to the oven and bake for an additional 10-15 minutes to heat through.