In a medium saucepan, combine cranberries, water, brown sugar, and leaves from 2 sprigs of thyme. Bring to a boil and cook for 2 minutes, or until cranberries begin to break down. Refrigerate to cool.

In a saute pan, cook pancetta over medium heat until browned. Remove and place on a paper towel to drain. Set aside.

Preheat oven to 375°F. Fit puff pastry into a 14”x5″ tart pan. Prick all over with a fork and brush with egg white. Bake for 8 minutes or until shiny and starting to puff up. Remove from oven.

Spread cranberry sauce evenly over puff pastry. Top with sliced brie and pancetta. Return to oven for 15 minutes, or until puff pastry is golden brown. Sprinkle with remaining thyme leaves. Serve warm.