I often use bought puff pastry to make a topping for a chicken pie. However, I tend to find that the pastry is fully cooked on the top but the underside of the pastry remains almost raw. How can I avoid this?
A few points to consider...
1) Try docking the pastry. Docked portions of pastry will rise more than undocked portions. This will promote even cooking.
2) In general, to cook food more evenly, one should cook longer at a lower temperature. The problem is that the dough on the bottom of your crust is not reaching a high enough temperature by the time the top of your crust is done cooking.
3) Puff Pastry is notoriously finicky. Be sure to handle the dough according to puff pastry best practices to ensure the layers do not collapse and stick together.
Pepperidge Farm has a tutorial website (http://www.puffpastry.com/videos-and-tips#howto-demos) to help people with puff pastry issues, but it doesn't appear to cover much detail.
I assume you are add pastry to the top of an oven proof dish filled with your chicken pie!
Have your rolled pastry ready in the fridge.
If you have a read of this it'll give you an idea of how puff pastry is made! I wrote it a long time ago but nothing's changed since then!! ;)