Start heating your oven to 200 C / 400 F / Gas Mark 6.
Make squares from the puff pastry, making a border around each edge. Bake them for 10 to 15 minutes until golden and puffed. Cool, then gently press down the centre.
Make a dressing of the olive oil, balsamic vinegar, garlic and basil.
Just before serving, fill the tomato squares with tomato slices, garnish with black olive halves, then drizzle the dressing over.