Carefully cut the spaghetti squash in half lengthwise and scoop out the seeds.
Place the squash halves cut-side down on a baking sheet and bake for 30-40 minutes, or until the flesh is tender.
While the squash is baking, in a medium saucepan over medium heat, combine the shredded chicken and Buffalo sauce. Stir in the cream cheese until melted and combined.
Once the spaghetti squash is done, remove it from the oven and let it cool for a few minutes. Using a fork, scrape the flesh to create spaghetti-like strands and place them in a large bowl.
Add the chicken mixture to the bowl with the squash strands. Mix in half of the cheddar cheese, salt, pepper, and half of the green onions.
Spoon the mixture back into the squash shells, then top with the remaining cheddar cheese and blue cheese crumbles, if using.
Return the stuffed squash to the oven for an additional 10-15 minutes, or until the cheese is melted and bubbly.
Remove from the oven, garnish with the remaining green onions and cilantro, if desired, and serve hot.
Notes
Adjust the amount of Buffalo sauce to your taste preference.