Cut the spaghetti squash in half lengthwise, then scoop out the seeds. Place both halves on a baking sheet, face-up, and bake for 30 minutes.
In a large bowl, add chicken, buffalo sauce, ranch dressing mix, and blue cheese crumbles. Using tongs, mix to combine.
Remove the spaghetti squash halves from the oven. Using forks, shred the guts to create spaghetti strands. Add these spaghetti strands to the chicken mixture, then toss to combine.
Add the spaghetti squash/chicken mixture into the spaghetti squash boats, and bake for 15 minutes.
Optionally garnish the squash boats with shredded mozzarella cheese, then serve and enjoy.