Place the leeks, garlic and bacon into the Thermomix bowl. Chop on Speed 5, 3 seconds.
Add the butter and saute for 5 minutes, Varoma, Reverse, Speed Soft.
Add the chopped chicken and cook for a further 5 minutes, Varoma, Reverse, Speed Soft.
Add the cooking cream, water and chicken stock and cook for 20 minutes, 100 degrees, Reverse, Speed Soft.
Divide the mixture equally between 5 ramekins (or 1 large casserole dish).
Cut the puff pastry into long strips and place in a criss cross patterns over the top of the pies (leaving small gaps to allow the steam to escape).
Brush with the egg and bake in a 200 degree celsius (fan-forced) preheated oven for 25 minutes or until golden.
Notes
I used Bulla cooking cream in this recipe as it doesn't curdle when cooked. If the mixture is too runny for your liking when it's finished cooking in the Thermomix, dissolve 2 tbs cornflour in a little water and mix through on Speed 2, Reverse before diving between the ramekins. If you make 1 large pie (rather than individual ones), you'll need to increase the cooking time in the oven to approximately 35 minutes.