You reserve 1 ¾ cups reserved water, and slowly stir it in the same time you add the milk.

‘Cool’ is standard lingo in cooking – it means: not hot, just warm, room temperature – the reason why you want to have it cooled is so that you don’t melt the fat in the raw pastry dough.

Cooking is more of an art and baking is more of a science. Given that information, estimated time to thicken the filling is based on preference. If you think the filling is thick enough, then it’s thick enough. If you want it thicker, keep cooking. If you screwed up and want it less thick, then add a bit more stock. That is basic common sense.

With regard to frozen butter – there is nowhere that you need frozen butter in this recipe. Are you talking about the pie pastry recipe? If so, leave your comment there and not on this one.

I hope that helps. This recipe is just fine the way it is. If you need clarification, then ask. Don’t go and crap all over it b/c you don’t know how to cook.