Creamy Maderia Chicken

• 3 chicken breast without skin (halves frozen)
• 1 onion
• 120 gr skim
• 120 gr swiss cheese (finely shredded)
• 80 gr mushrooms (sliced)
• 60 gr onion (chopped)
• 5 ml vegetable oil
• 5 ml worcestershire sauce
• 2 ml chicken bouillon crystals low sodium
• 1 gr black pepper