Remove roasts from pan, place on carving board and cover with foil. Remove bay leaf from pan and add sliced mushrooms to pan. Place Dutch oven over medium high heat. Meanwhile, add remaining beef broth and bring mixture to a boil. Adjust seasonings. In a bowl, combine cold water and flour and, using a whisk, combine well, making sure there are no lumps at all. With broth at a full boil, and whisking continually, pour flour mixture slowly in a thin stream into the boiling broth. Whisk and continue adding flour mixture until gravy is the consistency you like best. Reduce heat and allow gravy to cook for a few minutes. Carve meat across grain of meat and serve with mushroom gravy immediately. Makes 12-16 servings. Enjoy!