Steam cauliflower until soft then transfer to a food processor or blender, puree the cauliflower with the garlic, butter, salt, pepper, and egg yolk.
While the cauliflower is steaming, preheat a large skillet over medium high heat. Add oil to pan with beef. Season meat with salt and pepper. and brown with carrot and onion until the meat is no longer pink. In a separate saucepan cook butter and xanthan gum together combining well. Whisk in broth and tamari. Thicken gravy about 1 minute. Add gravy to meat and vegetables. and stir in the peas.
Preheat broiler to high. Put meat mixture into a rectangular or round baking dish and spread cauliflower over the meat as evenly as possible being careful not to let meat show through. Broil 6 to 8 inches from the heat until potatoes are evenly browned.