Preheat oven to 400º F
With a knife, carefully score squash lengthwise where you’re going to cut it in half. Poke a few holes along the score.
Microwave the squash for 5 minutes. Allow to cool.
Carefully cut the squash in a half. Scoop out the seeds.
Brush the inside of both halves of the squash with olive oil. Season with salt and pepper.
Place the two halves cut side down on a baking sheet lined with parchment paper.
Roast the squash until tender, about 30 minutes. Allow several minutes to cool.
Using a fork, scrape the insides to create a spaghetti-like texture. Leave insides in the squash.
Heat oil in a skillet on medium-high heat. Add onions and cook until translucent, 5-8 minutes.
Stir in the minced garlic and cook for an additional 30 seconds.
Add the ground beef. Season with salt. Cook and mix until cooked through, while breaking the beef into small crumbles, 5-8 minutes.
Stir in the crushed tomatoes and Italian seasoning. Bring to a simmer.
Spread the tomato/beef mixture evenly between the two squash halves.
Sprinkle the cheese evenly between both halves.
Bake until the cheese is melted, about 5 minutes.
Garnish with chopped parsley. Serve immediately and enjoy!