Preheat oven to 400 degrees. Cut squash in half lengthwise. Remove seeds. Place cut side down on a baking sheet, and bake for 25 minutes.
While squash is baking, brown ground beef over medium high heat. Drain, and set aside.
While your squash and beef are cooking, prepare vegetables. In a large sauce pan, begin to saute red onion, tomatoes, and garlic with avocado oil. Add seasonings. Once onions begin to turn translucent, add spinach and cook down.
Once squash is done, remove from oven and shred the meat of the squash with a fork. Add to pan with sauteed veggies. Add meat, and egg. Mix together thoroughly.
Pour mixture inside a 9 x 9 baking dish, and cook at 400 for 15 minutes.