While squash is roasting, heat oil in a large sauté pan over medium heat. Add onion and garlic and cook until fragrant, about 4-5 minutes. Add ground turkey and taco seasoning to the pan and cook, breaking meat apart with your spatula. Once turkey is cooked through and no longer pink, add black beans, salsa, cilantro, tomato paste, jalapeño, chili powder, pepper and sea salt to the pan. Stir until combined. Remove from heat and set aside.
One squash is roasted and cool enough to touch, remove spaghetti strands from the peel and add the squash to the pan with ground turkey mixture. Toss to combine then transfer to a 8x8 or 9x9 square baking dish. Sprinkle cheese on top.
Bake in the oven for 15-20 minutes at 375°F, or until spaghetti squash bake is warm throughout and cheese is melted.
Serve topped with fresh cilantro, jalapeño, green onions, chopped tomatoes, avocado and/or sour cream.