Preheat oven to 300 F. Season Roast with salt, black pepper, garlic powder, paprika, celery salt, chili powder and cayenne pepper. Add onions, celery, carrots and beef roast to pan. Add potatoes and bay leaves and sprinkle the tops of the potatoes with salt and pepper. Add Beef Stock. cover pot with lid or aluminum foil and bake for 2 1/2 hours or until internal temperature is 145 F. for medium rare or 160 F. internal temperature for well done. You can also cook this in a crock pot too on low for 6 hours or high for 4 hours or until desired internal temperatures are met.  Remove the potatoes and place on a serving platter. Remove the roast and allow to rest 15 minutes before slicing. Remove carrots and any onions and celery wanted. To make the gravy. Strain the reserved liquid and discard the leftover onions and celery. Add 1 cup of reserved liquid back into the pot and add beef stock and bring to a boil. In a small bowl, combine cornstarch and water and whisk into stock mixture and boil until liquid starts to thicken. Serve gravy with pot roast, carrots and potatoes.