Place sliced tomatoes on a non-stick baking tray and drizzle with olive oil; season with salt and pepper then place into the oven.
Roast for 20 minutes or until the tomatoes are soft and caramelizing around the edges.
Remove from the oven and allow to cool slightly; turn the oven down to 325°F.
Roll pastry out thin and place on a paper-lined baking sheet; score the edges to make a border; make sure not to slice through the pastry. Then bake halfway (for approximately 10 minutes); remove from the oven.
place tomatoes and mozzarella on the pastry, alternating the two.
brush the edges of the pastry with the beaten egg.
Drizzle a little olive oil over the tomatoes and mozzarella; season with salt and pepper.
Place back in the oven for approximately 10-15 minutes; until the pastry is crisp and golden.
Remove from the oven and top with fresh basil leaves.