Preheat oven to 400 C.
Roll out the puff pastry into a thin layer (about 12 x 12 inches, estimate no need to measure).
Put the brie wheel in the middle, with 2 tbsps of apple butter on top, and pile the walnuts.
Wrap the puff pastry around the brie. I actually cut off 2 inches off each side ( 10 by 10 sheet) and stretched the puff pastry around the brie. This is because I wanted a thinner layer of puff pastry. If you want more puff pastry/ a thicker crust, don't cut it and add 5 minutes to the baking time.
Brush the egg wash on the brie.
Bake the brie for 20-30 minutes.
Let the brie sit for 10 minutes and cut right in.
Serve with crackers and enjoy!