Place a sheet of puff pastry onto a baking sheet lined with parchment paper. Spread the vegan nutella all over. Place the second puff pastry over the top. Shape into a tree, and then cut the branches but cutting out 1-inch slits on both sides, keeping the middle intact. If you think you'll find this hard to do, lightly score a trunk onto the large triangle, making sure the top is more narrow, and the bottom side of the tree is wider.
To create the branches, twist the puff pastry strip 1-3 times. The bottom branches should have fewer twists, and the ones at the top will probably only have 1-2. With the excess puff pastry, cut out stars with a cookie cutter. One larger star for the top of the tree, and fewer smaller ones to decorate the tree trunk with. Press the stars onto the tree. In a small bowl combine, 1 tbsp melted butter with the oat milk. Brush all over the puff pastry tree and stars. Bake for 25-30 minutes or until golden.
While the Christmas tree bakes, mix the granulated sugar with ground cinnamon. Brush the freshly baked, warm tree with the remaining 1 tbsp of butter. Sprinkle the cinnamon-sugar mixture all over. Enjoy warm!!