Preheat the oven to 400°F.
Cut the squash in half lengthwise and scoop out the seeds with a spoon, discard.
Place the halves, flesh side down in a 13 X 9 pyrex dish and pour a little water around the squash to cover the bottom of the dish.
Bake for 35-45 minutes depending on the size of the squash. The squash is ready when the flesh can be easily scraped with a fork.
Scrape the inside of the squash with a fork to remove spaghetti- like strands. Place in a large bowl and set aside.
Heat the butter and olive oil in a nonstick pan over medium heat. Add garlic and saute for 1 minute. Add shrimp, salt, red pepper flakes and pepper. Continue to cook, stirring often for a couple of minutes until shrimp turn pink, around 3-4 minutes.
Add white wine, lemon zest, lemon juice and lemon slices. Bring to a boil and continue to cook for 1 minute. Add the spinach and stir. Add the spaghetti squash noodles and toss with shrimp. Cook for another minute or two until heated through.
Remove from heat, add parsley and parmesan and toss. Season with salt and pepper if desired. Enjoy!