Preheat oven to 375.
Roll out dough (I generally defrost the sheet and then roll it on the counter without flour or anything).
Spray round tart pan with Pam and lay dough in pan, lettering edges flop over sides of pan.
Spear dough with fork in several places (I spear it a lot).
Coat bottom, top and all sides of brie rind with mustard.
Bring up edges of dough around the cheese, leaving a 2 inch hole at the top exposing cheese.
Pierce outside of dough with fork.
Mix egg and 1 T cold water and base pastry, coating all edges, seams and outside shell to keep pastry from splitting during baking process.
Bake 45 minutes, let stand for 15 minutes.