Preheat the oven to 375 F (190 C) degrees. Unroll puff pastry and transfer to a baking sheet lined with parchment paper.

With a small sharp knife, lightly mark the pastry about 1 cm from the edges to create a border. Don't cut all the way through the pastry, this is just to score an edge for the beautiful golden crust to come. Brush the entire pastry with butter.

With your sharpest knife, slice zucchini as thinly as possible. Arrange them in overlapping rows on stop of puff pastry, staying within the scored edge.

Slice mozzarella into medium slices and evenly lay over zucchini. Using a kitchen scissor, roughly chop thyme on top of cheese. Sprinkle with white pepper.

Bake tart for 25 minutes until edges are golden.