If using fresh tomatillos, prepare by washing and removing husks. Place in saucepan, cover with water and simmer until tender, about 5 to 7 minutes; drain. If using tomatillos, drain and discard liquid.
For sauce, mince garlic, jalapeños, cilantro and onions in food processor or blender. Add drained tomatillos, sour cream, yogurt, honey and salt; purée.
Mix in green chilies and set aside. Soften tortillas either by frying on both sides in a small amount of vegetable oil, by wrapping in foil and placing in hot oven until hot, or by placing in microwave oven until heated.
In the center of each tortilla, place about 2 tablespoons each of chicken, sauce and cheese. Add about 2 teaspoons chopped hazelnuts. Pour 1/4 of the sauce in the bottom of a greased 9×12-inch baking dish. Place filled enchiladas in dish and pour remaining sauce over top.
Sprinkle with remaining cheese and then with hazelnuts. Bake in a 350º oven until heated through, about 20 minutes.