Make the Pesto: In a food processor, combine the fresh basil, olive oil, minced garlic, toasted pine nuts, and grated Parmesan cheese. Blend until smooth. Season with salt and pepper to taste. Set aside.
Prepare the Puff Pastry: Preheat your oven to 400°F (200°C). Roll out the sheet of puff pastry on a lightly floured surface to smooth out any creases.
Form the Wreath: Using a pizza cutter or sharp knife, cut the puff pastry into long strips (about 1-2 inches wide).
Assemble: Take one strip of puff pastry and spread a thin layer of pesto on it. Place a mozzarella ball at one end and roll the strip up tightly, creating a pinwheel. Repeat with remaining strips.
Create the Wreath Shape: On a parchment-lined baking sheet, arrange the pinwheels in a circular wreath shape, overlapping them slightly so they form a full circle.
Egg Wash: Brush the top of the wreath with the beaten egg to give it a golden color while baking.
Bake: Place the wreath in the preheated oven and bake for 20-25 minutes or until golden brown and puffed up.
Garnish: Once baked, allow it to cool slightly. Garnish with halved cherry tomatoes and fresh basil leaves for a festive touch. Serve remaining pesto on the side for dipping.