Preheat your oven to 375°F and prepare a large baking sheet by lining it with parchment paper. In a mixing bowl, combine the softened cream cheese, spinach, artichoke hearts, Parmesan cheese, garlic, and sour cream. If desired, add lemon zest and crushed red pepper flakes for extra zest and heat. Mix thoroughly, then season the filling with a generous pinch of salt and a grind of fresh black pepper.

Lay the puff pastry sheets flat on the prepared baking tray. Using a sharp knife or a pizza cutter, carefully carve both sheets into identical Christmas tree shapes, saving the excess trimmings. Remove the top pastry tree and set it aside. Spread the prepared cream cheese mixture evenly over the bottom tree layer, ensuring full coverage. Sprinkle the mozzarella cheese over the filling, then place the second tree cutout on top to form a layered design.

From the reserved pastry scraps, cut out a star shape and place it at the top of the tree. Next, use a sharp knife or pizza cutter to slice 1/2-inch wide "branches" along both sides of the tree, taking care to leave a 1-inch uncut section running down the center to maintain structure. Gently twist each branch to create a spiral effect for a festive look.

In a small bowl, whisk together the melted butter and garlic powder. Generously brush this mixture over the entire pastry tree, including the star. Bake in the preheated oven for approximately 30 minutes or until the tree turns golden brown and puffy.

Remove from the oven, let it cool slightly, and serve warm for a visually stunning and delicious appetizer.