Preheat oven to 400 Degrees.

Roll out the puff pastry into a 12×12 inch square. Cut three small 1/4″ strips from three sides of the puff pastry and set those aside. You will braid them together for a decorative topping.

Gently cut the top rind off the brie cheese and discard. Top the cut side of the brie with blackberries, and drizzle with the blackberry jam. Sprinkle on thyme, and black pepper. Lay the puff pastry over the top of the cheese and berries. Before you fold the puff pastry under the cheese, brush the edges of the puff pastry with a mixture of egg and water. This will glue the pastry together. Fold the puff pastry under the brie and seal.

Brush the rest of the puff pastry with the egg wash. Braid the three strips of the remaining puff pastry and set it on top of the en croute. Brush this with egg wash.

Bake for 30-35 minutes, or until dark golden brown. Remove and serve with crackers, or bread crisps.