Preheat oven to 325° and lightly grease a large deep baking dish with cooking spray.
In large skillet over medium heat, heat oil. Add onion and cook until soft, about 5 minutes.
Season with salt and pepper then stir in garlic and herbs. Cook until fragrant, 1 minute. Remove from heat and let cool slightly.
In a large bowl, mix ground turkey, breadcrumbs, milk, Worcestershire, egg, and cooked vegetables until combined. Season with salt and pepper.
On prepared baking dish, form meat mixture into a loaf.
In a small bowl, stir ketchup and brown sugar until combined, then brush over loaf.
Bake until internal temperature reaches 160°, about 1 hour 20 minutes.
