Preheat the oven to 400°F. Coat a 3-quart baking dish with nonstick cooking spray.
Heat the oil in a large skillet over medium-high heat. Add the onion and garlic and cook 5 minutes or until the onion is tender.
Stir in the ground turkey and cook 8 minutes, or until the meat is browned and crumbly. Stir in the frozen vegetables.
Whisk together the broth, Worcestershire sauce, soy sauce, tomato paste, and flour in a large liquid measuring cup. Add the mixture to the ground turkey and vegetables and bring to a simmer. Cook 5 minutes or until the gravy is thickened. Season with salt and pepper to taste.
Transfer the ground turkey mixture to the prepared baking dish. Dollop the mashed potatoes over the top and spread to an even layer.
Bake the shepherd’s pie for 20 to 25 minutes, or until the edges are bubbly. If desired, increase the oven temperature to broil and broil for 2 to 3 minutes to brown the mashed potatoes. Remove from the oven and garnish with parsley before serving.