Preheat the oven to 375° F. Cut open the spaghetti squash lengthwise, drizzle with olive oil, and sprinkle with salt and pepper. Place the squash face-down in a 9×13 inch casserole dish.
Bake the squash in the oven for 40-45 minutes, until a fork goes through it easily. While the squash is baking, prepare the other ingredients.
Heat a small amount of cooking oil in a frying pan. Add the ground chicken, and stir fry on medium heat until brown – about 15 minutes. When the meat is cooked, add taco seasoning and stir to coat.
Heat cooking oil in a large pot. Add garlic and onion, and stir fry over medium heat for 2-3 minutes.
Add red pepper and all spices and continue stir frying for a few more minutes, until the pepper begins to soften.
Add black olives, cherry tomatoes, and spinach. Stir until the spinach begins to wilt. Remove from heat.
When spaghetti squash is cooked, remove from the oven, and turn the oven temperature up to 400° F. Using a fork, scrape the flesh of the squash into a bowl.
Put the spaghetti squash, chicken, salsa, and egg into the large pot with the cooked vegetables. Mix well until all ingredients are combined.
Pour the mixture into the 9×11 inch casserole dish used to cook the squash. Bake in the oven for 15 minutes. When the casserole comes out of the oven, top with green onion, and serve with avocado and salsa.