Turkey Chili and Sweet Potato Shepherds Pie

Name: Turkey Chili and Sweet Potato Shepherd's Pie
Ingredients: 2 1/2 pounds sweet potatoes, 4 to 5 potatoes, peeled and cubed; Salt; 2 teaspoons orange zest; 4 tablespoons butter, cut into pieces; 1 cup creme fraiche or sour cream; Freshly ground black pepper; Freshly grated nutmeg, to taste; 2 tablespoons extra-virgin olive oil; 2 pounds ground turkey; 1 large onion, chopped; 2 small chile peppers, red fresno, jalapeno or serrano; 1 red bell pepper, chopped; 2 to 3 large cloves garlic, chopped; 3 tablespoons chili powder (recommended: Gerhardt's); 1 tablespoon smoked sweet paprika; 1 tablespoon ground cumin, a palmful; 1 tablespoon ground coriander, a palmful; 1/4 cup tomato paste; 2 to 3 cups turkey or chicken stock; 2 cups shredded sharp yellow Cheddar