Preheat oven to 350 degrees.
In a large bowl, add the meat, mushroom and remaining 10 ingredients. Mix until well combined.
Place mixture into 7 x 5 inch loaf baking pan or shape into free form loaf and place on a parchment lined sheet pan. Place into preheated oven and bake for 45 minutes.
In a small bowl, combine milk and cornstarch; set aside.
In a large skillet, melt butter over high heat. Add the mushrooms and onions; cook and stir over moderate heat until the mushrooms are golden, about 10 minutes.
Add the flour and stir to coat, cook for 5 minutes. Stir in beef broth and bring to a simmer and add Worcestershire sauce.
Cook over high heat, stirring constantly, until slightly thickened, about 1 minute.
Taste for seasoning and adjust to taste with salt and pepper.
