Add the basil, water, nuts, garlic, lemon juice, nutritional yeast, and sea salt to a food processor or small blender and mix on high until smooth.
While blending, add olive oil a little at a time, controlling the consistency. Scrap down sides as needed. Set aside.
You can skip the first two steps if you buy store-bought pesto.
Place one sheet of puff pastry on a lightly floured surface.
Spread your pesto evenly on the puff pastry.
Cover with another sheet of pastry.
With a sharp knife, cut a large triangle - the tree shape.
Use the leftovers to cut out the trunk and the star for the top.
Make the branches of the tree by slicing into the puff pastry from the side, being careful not to slice all the way through.
Twist every branch.
Press the edges of the twisted branches down into the puff pastry so they don’t pop up.
Transfer the tree to the baking tray.
Add the trunk to the bottom and star to the top and press the edges to the tree.
Bake for about 25 minutes until golden at the edges.
Sprinkle with peppercorns, cranberries and decorate with rosemary.