Carefully cut the spaghetti squash in half lengthwise and scoop out the seeds. Rub the inside of each half with olive oil and season with salt and pepper. Place the squash cut-side down on a parchment-lined baking sheet and bake at 400°F for 40 to 50 minutes, or until tender.

Place the sun-dried tomatoes in a heat-safe bowl and cover them with hot water. Let them soften for about 10 minutes, then drain the water and chop them into small pieces.

Add the olive oil to a large skillet over medium heat on the stovetop. Sauté the diced onion and crushed garlic until translucent and fragrant, about 2-3 minutes.

Reduce the heat to low and add the milk, light cream cheese, chopped sun-dried tomatoes, grated Parmesan, tomato paste, oregano, basil, salt, pepper, and optional crushed red pepper flakes. Stir until everything is well combined and the cream cheese is fully incorporated into the sauce.

Make a cornstarch slurry by combining 1 tablespoon of cornstarch with 1 tablespoon of cold water. Pour the cornstarch slurry into the skillet and stir occasionally until thickened.

Once the spaghetti squash is done, let it cool slightly, then use a fork to scrape it into long, spaghetti-like strands. Place the strands in a bowl and set them aside.

Add the fully cooked, shredded rotisserie chicken and the spaghetti squash strands to the skillet. Gently mix everything until it is well incorporated and heated through.

Top with optional fresh basil leaves, serve warm, and enjoy!