sweet potatoes, peeled, cubed
celery stalk, finely chopped
Bring large pot of water to a boil, cook potatoes until tender, about 20 minutes; drain.
Add milk, butter, nutmeg, salt and pepper to potatoes and mash until smooth and fluffy.
Saute onions, carrot and celery in oil over medium heat for 5 minutes.
Sprinkle with thyme and chili flakes.
Add ground beef and cook until no longer pink.
Stir in roast beef, sprinkle with flour, then pour in beef broth, tomato paste, worcestershire sauce, salt and pepper; stir well.
Reduce heat and cook for 5 minutes.
Spread meat mixture in a square casserole, spread mashed potatoes over and bake 35-45 minutes until heated through.
Place under broiler for 1 minute.