1. In a bowl, combine ground chicken, bread crumbs, onion, egg and seasonings.
2. In a skillet, cook mushrooms in butter for 3 to 4 minutes.
3. add to chicken mixture; mix well.
4. Spoon into an 8 x 4 inch (1.5 L) loaf pan and smooth the surface.
5. Bake at 350° F (180°C) for about 1 1/4 hours until a meat thermometer registers 185°F (85°C).
6. Spread chili sauce over the surface after baking 1 hour.
7. Let stand for 10 minutes before slicing.