Toast the pine nuts in a small frying pan over a low heat. Add into a food processor with the basil, parmesan and chopped garlic and blitz until puréed.
Preheat the oven to 180oC and line a baking tray with baking parchment. Put the puff pastry sheet onto the parchment and prick all over with a fork. Fold the edges in to make a border and brush with beaten egg.
Spread the pesto over the base and bake for 20-25 minutes.
When the tart is crisp, top with lines of tomato and mozzarella and sprinkle over torn basil and cracked black pepper. Serve hot or cold.