Preheat your oven to 180°C fan/200c. Line a rectangular baking tray with parchment and unroll your puff pastry onto it.
Use a vegetable peeler to create thin courgette ribbons. Season them with salt, pepper, lemon zest, and a drizzle of olive oil. Set aside to soften slightly.
In a bowl, mix one torn ball of mozzarella with the crème fraîche, lemon zest, salt and pepper until smooth and creamy. This forms the base layer of your tart.
Score a 1cm border around the pastry to help it puff up into a raised crust. Prick the base inside the border with a fork.
Spread the mozzarella crème fraîche mixture over the centre of the pastry, leaving the border clear. Drizzle with green pesto, then pile the courgette ribbons generously on top, arranging them with good height and texture.
Using a pastry brush or a clean finger, brush the pastry edges with the beaten egg.
Bake in the preheated oven for around 15-20 minutes or until the pastry is golden and crisp and the courgettes are turning golden.
Once baked, top with more torn mozzarella, toasted pine nuts, a final drizzle of pesto and a grating of parmesan.
The video below will help with this recipe.