roast the spaghetti squash preheat oven to 400°f. slice the spaghetti squash in half lengthwise, scoop out the seeds, and place cut side down on a parchment-lined baking sheet. bake for 40–42 minutes or until tender. let cool slightly, then use a fork to scrape out the strands into a large bowl. set aside.

prepare the tomato mixture heat a drizzle of olive oil in a large pan over medium heat. sauté the diced onion and garlic for about 3–4 minutes, until soft and fragrant. add the halved tomatoes and sauté for another 6 minutes, until the tomatoes are tender and starting to burst. season with a pinch of sea salt and pepper.

combine and mix reduce heat to low and stir in the tomato paste, marinara sauce, and roasted spaghetti squash. mix until fully combined. fold in 1/2 cup shredded mozzarella and chopped basil. taste and adjust seasoning if needed.

bake it up transfer the mixture to a greased 8x8 or similar sized baking dish. top with more shredded mozzarella. bake at 375°f for 22 minutes until hot and bubbly, then broil for 1–2 minutes if you want a golden cheesy top.

serve garnish with more fresh basil and enjoy warm! leftovers can be stored in an airtight container in the fridge for up to 4 days.