In a small skillet, melt the butter over medium-high heat. Stir in the apples and cook until the apples are tender, approximately 5 minutes. Add the sugar, walnuts and cranberries, stirring until the sugar is dissolved. Cook the mixture down until the liquid has evaporated, approximately 10 to 12 minutes. Remove from heat and cool.

Preheat oven to 375 degrees. Line a rimmed baking sheet with a Silpat or parchment paper.

On a clean, lightly floured surface, roll out the puff pastry until it’s approximately one-quarter inch thick. Cut the pastry into a 10-inch round and place the round on the lined baking sheet.

Cut off the top of the wheel of Brie. Place the Brie cut side up in the center of the puff pastry round. Top the Brie with the apple cranberry mixture (I used about two-thirds of the mixture and saved the rest to serve alongside the finished dish). Fold up the sides of the puff pastry over the sides of the cheese, pinching the edges together to form pleats and leaving a slight gap in the center. Make sure you pinch the pleats together tightly, they will slightly expand out as it bakes.

In a small bowl, mix together the beaten egg and water. Brush the puff pastry with the egg wash.

Bake for approximately 40 to 45 minutes, or until the pastry if golden brown. Serve with the remaining apple mixture and crackers or toasted bread.