Add the chicken to a pot together with the carrots, mushrooms, green beans and celery. Add enough water to cover the ingredients and add the Knorr chicken stock pots, keeping a little aside for brushing on the pie lids in 9, below.
Boil for 15 minutes before draining the chicken stock into a bowl and setting the chicken and vegetables aside.
In a frying pan, melt the butter and add the chopped onion. Add the flour, garlic salt and black pepper. Slowly pour in 1 3/4 cups of the chicken stock and the milk, all the while stirring continuously.
Simmer the sauce until it is thickened.
Grease a large 6-cup muffin tin (or use individual ramekins). Roll out the puff pastry using a rolling pin and flour. Cut out circles from the dough, rolling out each one until it is big enough to be pressed into a muffin tin cup with an overhang of 1,5 cm.
Use an empty, clean can to cut out the pie lids. You’ll need 6 pie lids.
Combine the cooked chicken and vegetables with the sauce for the pie filling.
Spoon the filling into each pie case and close the pies with the lids, making sure to seal the edges by pinching them together. (Note: If freezing the pies, do so at this stage for best results, but allow the filling to cool completely before adding it to the pastry casings.)
Brush the pie lids with Knorr chicken stock from a stock pot and bake for 30 minutes at 180 until golden brown.
Serve warm with a fresh green salad or steamed veggies.