Preheat oven to 400 degrees.
Cut you squash in half and scoop out the seeds and the guk inside. Place it on a cookie sheetface down, and bake it until it is fork tender (about 40 mins)
Bring a medium sized potof salted water to a boil and boil your chicken until cooked through (20-25 mins.) Let cool.
While your chicken and squash are cooking, dice the red onion and throw it into a grill pan on High heat, until it is has nice grill marks. (about 5 mins.) Set aside.
Dice the green onion and cilantro and grate the cheddar cheese and set everything aside.
Once your squash has cooked, it's time to throw everything together.
Spray a casserole dish or cast-iron skillet with cooking spray.
Using 2 forks, shred the chicken into small pieces and throw into a large bowl.
Add in the spaghetti squash, grilled red onion, green onion, cilantro, salt, pepper, chile powder, cumin, garlic, paprika, red pepper flakes and 1/2 cup reduced fat cheddar cheese, reserving the rest for later
In a medium sized bowl, combine the BBQ sauce and Greek yogurt
Pour the yogurt mixture over the squash mixture and mix until well combined.
Pour into the casserole dish and top with remaining cheddar cheese.
Bake at 400 degrees for 25 minutes. Then turn your oven to HIGH broil and broil for around 5 minutes, until the topping is brown and bubbly.