Turkey Mushroom Gravy

1 . Stage

Melt butter in a large stock pot over medium-low heat, and cook mushrooms until they are browned and butter is clear, 1 to 1 1/2 hours. Remove mushrooms, coarsely chop them, and set aside. There should be about 1 cup of butter left in the stock pot; whisk flour into butter, and gently cook over low heat until flour mixture turns a mahogany brown color, about 20 minutes. Whisk in chicken broth; bring mixture to a simmer to thicken stock.

2 . Stage

Pour turkey drippings into a saucepan, then cook and stir onions and celery in drippings over medium-low heat until onions begin to turn brown, about 20 minutes. Stir drippings and vegetables into thickened stock. Bring gravy to a gentle boil, reduce heat, and simmer for about 20 minutes to blend flavors. Stir in chopped mushrooms, then season to taste with salt, black pepper, and cayenne pepper.