Heat the oven to 400°F (200°C). Line a large baking sheet with parchment and whisk the egg with water in a small bowl. Have everything ready before you open the pastry so it stays cold and easy to cut.

Lightly flour your work surface and unroll one puff pastry sheet. It should feel cold but flexible. Cut a large triangle with a pointed top and wide base, then add a small rectangle at the bottom for the trunk. Transfer this tree shape carefully to the prepared baking sheet and save the scraps for extra twists.

Spread a thin, even layer of basil pesto over the tree, leaving a small border. You should see the pastry through the pesto. Sprinkle the Italian cheese blend evenly over the top, avoiding heavy mounds in the center so it bakes at the same rate as the branches.

Unroll the second pastry sheet. Use the first tree as a template and cut another tree the same size. Place it gently over the filled base, lining up the top and trunk first, then adjusting the sides so the edges meet without stretching the dough.

Press around the edges with your fingers to seal the two layers. Picture a wide vertical strip down the middle for the trunk. Leave that part uncut. From each side, slice horizontal “branches” from the outer edge toward the trunk, stopping before the center line so everything stays connected.

Lift each strip and twist it two or three times so the layers show. The branches should lie flat on the tray after twisting. If any strip tears, press it back together gently and twist a little less.

Use a pastry brush to coat the tree with egg wash, paying attention to the tips of the branches and the edges. Avoid puddles of egg in the cuts, which can bake into rubbery spots.

Bake for 15–20 minutes, until the branches have puffed, the trunk looks fully cooked through, and the top is deep golden at the edges. If the tips brown very quickly, cover the center loosely with foil and bake a few minutes more.

Let the tree cool on the tray for a few minutes so the cheese can settle. Transfer carefully to a board or platter. Scatter fresh basil leaves and cherry tomato halves over the branches, then serve warm and let guests pull off branches with their hands.