1. In a large skillet, heat oil over medium-high. Add onion and sauté until translucent, 6-7 minutes. Add garlic and cook until fragrant, 1 minute. Transfer to medium bowl and add turkey, breadcrumbs, mustard and parsley. Gently mix until combined and form into 8 patties.

2. Heat grill or grill pan to medium-high. Clean and lightly oil hot grill. Season patties with salt and pepper, then brush with oil. Grill covered, until cooked through, about 4 minutes per side; during last minute of cooking, top each burger with cheese and cover grill. Serve burgers on buns with desired toppings.