Preheat oven to 200 degrees celsius (fan-forced). Lightly grease 5 large ramekins and set aside.
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 over the whisked egg and sprinkle with sesame seeds. Bake for 25 minutes or until golden.