01Preheat oven to 400 F. Line a baking sheet with parchment paper. Slice the spaghetti squash in half lengthwise and scoop out the seeds and ribbing. Drizzle the inside of the squash with olive oil and sprinkle with salt and pepper. Place the spaghetti squash cut-side down on the baking sheet and use a fork or knife to poke holes in the skin. Roast for 30 to 40 minutes or until lightly browned on the outside, and the flesh is fork tender but still a little firm. (The time will vary depending on the size of the squash.)
02Remove from the oven and flip the squash so that it’s cut-side up. When squash is cool to the touch, use a fork to scrape and scoop the strands from the sides of the squash. Set aside.
03In a saucepan over medium heat, melt the butter. Add the garlic and cook for 1 minute or until fragrant. Add the heavy cream and milk. Let the mixture come to a simmer over low heat. Stir in the Parmesan cheese and parsley. If the sauce is too thick, add a little more milk.
04Reduce oven to 350 F. Coat a 9 x 13-inch casserole dish with cooking spray. In a large bowl toss together the spaghetti squash strands and sauce. Place squash in an even layer in the casserole dish. Sprinkle top with mozzarella cheese.
05Bake for 15 minutes or until cheese melts and the squash is warmed through. For a crispier cheese on top, place under the broiler for 1 to 2 minutes.