Preheat oven to 350 F.
Pierce spaghetti squash with a knife and roast for ~1-1/2 hours for 2 small (or until a knife easily pierces the skin).
While squash cooks, chop 1 onion & 1 seeded poblano.
In large sauté pan, heat 1T olive oil over medium heat. Add chopped poblano and onion, sauté until softened, about 2 minutes.
Add the following to the skillet:
1 lb ground bison (breaking apart as you cook) + 2tsp smoked paprika + 1tsp cumin + 1/2tsp garlic powder + 1tsp oregano + salt to taste. Cook until bison is cooked through.
Drain 15 oz can diced tomatoes, then add to skillet. Cook until warm and any liquid begins to thicken.
Once squash is cooked, carefully slice squash in half, lengthwise, allowing heat to escape. Place in fridge and allow to cool enough to handle.
While squash cools, roughly chop cilantro for ~1 cup.
Once cooled enough to handle, remove seeds from spaghetti squash halves. Then shred pulp with a fork.
Stuff each squash evenly with bison mixture.
Top each squash evenly with grated 1/2 oz cotija cheese (optional) and 1/4 cup cilantro.