Basic Shepherds Pie

• 5 sweet potatoes quartered
• 2 onions (diced)
• 1 stalk celery (finely chopped)
• 1 carrot (diced)
• 450 gr beef (lean ground)
• 450 gr roast beef (cooked diced)
• 80 ml beef broth
• 60 ml milk
• 34 gr tomato paste
• 30 ml worcestershire sauce