Line a large tray with baking paper and preheat your oven to 200℃/400℉ (or 180℃/350℉ for fan and convection ovens).
Unroll the first puff pastry sheet and place it onto your lined tray.
Melt the Biscoff spread in the microwave for 10-20 seconds until it becomes smooth and runny.
Spread the Biscoff spread over the pastry, ensuring you get it all the way to the edges. Then top with the second puff pastry sheet.
Use a sharp knife or pizza cutter to cut out your Christmas tree shape. Use leftover dough to cut out extra shapes if desired (I made a star for the top of my tree).
Create the tree branches by making small cuts on each side of the triangle from top to bottom, about 1 inch apart. Then carefully twist each branch away from you (see images or video for reference).
Beat the egg then use a pastry brush to brush it onto your tree and any extra shapes.
Bake your tree for around 20-25 minutes, or until it's golden brown all over. Baking time will depend on the size of your puff pastry sheets so just keep an eye on it while it's baking.
Once baked, dust the tree with icing sugar. Serve with warm Biscoff spread and enjoy!