Preheat oven to 375°F degrees. Lightly dust flour on top of a sheet of parchment paper.
Unfold one sheet of puff pastry on top of the parchment paper. Use a rolling pin (with a little flour on it) to gently roll out the puff pastry sheet into an 11 X 13 inch rectangle.
Spread the Nutella on top of the puff pastry sheet in a large Christmas tree shape (this does not have to be perfect) be careful not to go too close to the edge.
Carefully unfold the second sheet of puff pastry and place it onto a lightly floured surface. Roll it out into an 11 X 13 inch rectangle.
Gently place the second sheet of puff pastry on top of the first sheet of puff pastry that has Nutella on it. Press gently to seal the two sheets together.
Using a ruler, outline a Christmas tree shape and cut the outline with either a sharp knife or pizza cutter.
Place a ruler down the center of the puff pastry Christmas tree to use as a guide, leaving 1-2 inches in the middle of the tree.
Starting on one side, make horizontal slices into the sides of the Christmas tree triangle, leaving about 1 inch in between each slice. Do this to both sides of the tree, all the way to the top. Gently lift the parchment paper with the tree onto a baking sheet.
Starting at the bottom, twist the branches away from you, one or two times and then press the edges firmly onto the parchment paper. This will keep them from unraveling during the cooking process.
With the excess puffed pastry dough, you can spread more Nutella inside and use a star cookie cutter to make some star shaped pastries to add to the dessert later. One will be used as the star for the Christmas tree.
In a small bowl, beat the egg and use as an egg wash, brushing the top of the pastries. Use a fork to poke some holes on the middle flat section of the tree.
Bake the tree and the stars in the preheated 375°F oven for about 15 - 18 minutes or until puffy and golden brown.
Allow to cool slightly before sprinkling or sifting some powdered sugar right on top. Enjoy!