Preheat your oven to 400°F and line a large baking sheet with parchment paper for easy cleanup.
Slice the spaghetti squash in half lengthwise, scoop out the seeds with a spoon, and brush the cut sides with olive oil and a pinch of sea salt.
Place the squash halves cut-side down on the prepared baking sheet and roast for 35 to 40 minutes until the skin is easily pierced with a fork.
While the squash is roasting, heat a large skillet over medium heat and add the ground turkey, breaking it up with a spatula as it browns.
Once the turkey is cooked through, add the minced garlic, dried oregano, remaining sea salt, and black pepper, sautéing for 2 minutes until fragrant.
Stir the marinara sauce into the skillet with the turkey and reduce heat to low, allowing it to simmer and thicken for 10 minutes.
Remove the squash from the oven and use a fork to scrape the flesh into long, spaghetti-like strands directly into the skillet with the sauce.
Toss the squash strands thoroughly with the turkey marinara and serve garnished with chopped fresh basil.