For the puff pastry filled with tomatoes and mozzarella, unroll fresh puff pastry on baking paper and preheat the oven to 210°C. Lightly sauté the chopped shallot in olive oil. Quarter tomatoes, remove seeds and cut into small cubes, sauté briefly with shallot and season with salt, pepper and chopped garlic.
Add the mozzarella to the cooled tomato mixture and carefully fold in the basil leaves. Cut dough into 15 squares, size 8 x 8 cm (or 8 rectangles of 12 x 10 cm) and brush with beaten egg.
Place the filling in the center of the pastry squares, fold the pastry diagonally to form a triangle and press the edges well with the help of a fork. Bake the puff pastry filled with tomatoes and mozzarella on the middle rack for approx. 12 – 15 minutes until golden brown.