Season the chuck roast with salt and pepper.
Heat 1 tablespoon of oil in a large dutch oven over high heat. Add the beef and cook until browned on all sides. Work in batches if needed so that you don't overcrowd the pan.
Remove the beef from the pan and set aside.
Reduce heat to medium and add the remaining tablespoon of oil to the pan. Add the onion to the pot, stirring often, until softened about 5 minutes.
Add the seared beef, broth, bouillon granules, Worcesetershire sauce, garlic powder, and onion powder to the pot and stir well to combine.
Bring to a boil, reduce to a simmer, and cook, covered, for 1 ½ hours or until beef is tender.
Remove ½ cup of the beef broth from the pan into a small bowl. Sprinkle the xanthan gum over the top and whisk well to combine.
Pour the liquid back into the pot and stir well.
Continue cooking for 30 minutes to thicken.
Serve the beef tips and gravy over mashed cauliflower.