Chicken-vegetable Pot Pies

• 2 baking potatoes
• 1 poultry seasoning
• 600 ml water
• 290 gr pkg frzn mixed vegetables
• 240 ml skim milk
• 200 gr chicken breast (halves)
• 130 gr flour
• 120 ml nonfat buttermilk
• 50 gr celery (chopped)
• 40 gr mushrooms (drained sliced)