Preheat the oven to 190c and place a large baking tray in to heat up.
Roll out the sheet of pastry, keeping it on its baking paper.Use a sharp knife to cut a 1’’ border along the edges, being careful you don’t cut all the way through. Prick the bottom with a fork, the spread over the pesto, leaving the edges clean.
Slice the tomatoes approx 5mm thick, then arrange over the pesto layer. Sprinkle with some salt and pepper then brush the edges with the beaten egg to glaze. Transfer to the hot baking tray and bake in the oven for 20-25 minutes.
Serve scattered with some fresh basil leaves, a drizzle of oil and some salt and pepper.
