For the Gravy:
- 2 tablespoons butter
- 6 ounces white button mushrooms, sliced
- 1/2 yellow onion, diced
- 2 tablespoons all-purpose flour
- 3 cups beef broth
- 2 tablespoons ketchup
- 1 tablespoon Worcestershire sauce
- Kosher salt and freshly ground black pepper, to taste
