Slice Mushrooms or leave whole if small. Dice Chicken into bite size pieces. Gently fry Group 1 in saucepan to seal chicken. Add Group 2 and bring to a rolling boil until chicken is tender do not over cook. Replace liquid lost during cooking process. Bring back to heat. Mix Group 3 into a slurry and add to chicken mixture. Cook through for a further 2-3 minutes. Cool filling down then place in refrigerator until required.
Do not leave prepared Chicken Filling on bench uncovered during the cool down process.