Wash, cut spaghetti squash in half lengthwise and remove seeds.
Rub lightly with 1/2 Tbsp canola oil and place cut side down on baking sheet.
Bake for 35-45 minutes until fork tender.
Once cool to the touch, use a fork to scrape strings out of squash halves. Set squash strands and empty shells aside.
Sauce & Assembly
In large pot, heat remaining canola oil.
Add onion and cook until tender, but not brown, about 2 minutes.
Add garlic and cook 1 minute.
Add ground chicken, stir and cook through, about 3-5 minutes.
Stir in tomatoes, vinegar and seasonings. Bring to boil then reduce heat and simmer for 15 minutes to let flavours combine and sauce to thicken.
Remove from heat. Add spaghetti squash strands, half the Parmesan, half the mozzarella and half the basil or parsley. Mix well. Taste and adjust seasoning to your liking.
Spoon hot sauce mixture into empty spaghetti squash shells. Top with the remainder of the Parmesan and mozzarella.
Place under broiler until cheese is melted and toasted. About 2-4 minutes.
Remove from oven and top with remaining parsley or basil. Let rest for 5 minutes and enjoy.
Notes
Make Ahead Instructions: The spaghetti squash can be baked and sauce can be made 2-3 days ahead and stored in the fridge. The dish can also be assembled and stored for 2-3 days before baking. If ingredients are cold, bake the filled shells in a 350°F oven for 40-50 minutes.Because of the high water content of the spaghetti squash, I do not recommend freezing this dish before or after baking. Keep leftovers for up to 3 days in the fridge. Reheat leftovers on stove top or in microwave.