Cook spaghetti squash. (I do this by cutting the squash in half, scraping out the seeds, and baking it at 350 degrees for 60-90 minutes. Scrape out flesh with a fork and save for later.
Add 1/3 cup of cooked spaghetti squash to 6 muffin cups, sprayed with cooking spray.
Whisk the eggs and egg whites together. Pour 1/4 cup of egg mix over each muffin cup filled with spaghetti squash.
Top each spaghetti squash cup with sliced tomatoes, chopped spinach, a sprinkle of parmesan cheese, and salt.
Bake at 350 degrees Fahrenheit for 40-45 minutes, or until egg is cooked all the way through and the top starts to become golden brown.
Remove from oven and eat warm! Can be stored in the fridge for 4-5 days. Reheat and eat warm.