Roll out the thawed puff pastry into a 12-inch rectangle, about ¼-inch thick, and transfer to a parchment-lined baking sheet. Brush with beaten egg.

In a mixing bowl, toss sliced heirloom tomatoes with olive oil, minced garlic, sea salt, and black pepper. Let rest for 5 minutes.

Spread seasoned tomatoes evenly over the puff pastry, leaving a generous ½-inch border. Layer with mozzarella and Parmesan cheese.

Preheat oven to 400°F (200°C) and bake the tart for 35-40 minutes, or until golden brown.

Remove from the oven and let cool for about 5-7 minutes. Sprinkle with torn basil leaves before serving.

Slice into wedges and serve warm as an appetizer or brunch dish.