Boil the sweet potatoes in salted water until tender, about 10-12 minutes. Drain and mash with butter or olive oil, milk, salt, and pepper. Set aside.
In a large skillet, cook the ground turkey over medium heat until browned. Add the onion, carrots, and garlic, and cook for another 5 minutes until softened.
Stir in the tomato paste and thyme, then pour in the chicken broth. Simmer for 10 minutes until the mixture thickens slightly.
Pour the turkey mixture into a baking dish and spread the mashed sweet potatoes evenly on top.
Bake for 20-25 minutes until the top is golden. Garnish with fresh parsley before serving.