Cook your chicken breast in the oven for 25-30 minutes at 200 °C. Leave to one side to cool.
Allow the chicken to rest for 10 minutes then shred it using 2 forks, like the do with your duck in the chinese, leave to one side.
Add some spray oil to a pan, allow to heat for about a minute and then add your mushrooms. Cook for around 3 minutes stirring regularly.
Take OFF the heat and add your flour, ketchup, mustard and puree. Stir through thoroughly.
Add your milk, stir through and then pop back on the heat
Slowly bring to the boil, stirring continuously
Add your chicken, stir through and season with salt and pepper. Add a teaspoon of parsley and allow to simmer GENTLY for about a minute.
Pop your pancake on a plate and nuke for 30 seconds, pour your filling on top and serve!