Preheat the oven to 400 degrees F and spray a baking sheet with cooking spray.
Slice your spaghetti squash in half lengthwise and scoop out the seeds, then spray the cut side of the squash with a little olive oil cooking spray and place cut side down on the baking pan.
Roast spaghetti squash for 30-45 minutes or until it is tender.
While the squash is cooking, sauté the onion, celery, and carrots until softened and mostly cooked through.
In a large bowl, combine the sauteed vegetables, chicken, hot sauce, ranch dressing, garlic powder, salt, pepper, eggs, and cheese.
Once the squash is cooked through, allow to cool slightly then use a fork to scrape the insides into your chicken mixture, making sure not to tear the skins.
Make sure that the spaghetti squash is well incorporated with the other ingredients, then divide the mixture between the spaghetti squash halves.
Bake at 350 degrees for 30-35 minutes, or until hot and bubbly.
Remove from the oven and garnish with the green onions and additional ranch or hot sauce if desired.