Heat the oven to 200°C fan. Unroll 275g ready-rolled puff pastry and cut into six pieces, then place on a parchment lined baking tray. Score a 1cm border around the edge of each pastry square, making sure you don’t cut all the way through. Bake for 15 minutes.
Turn the oven down to 180°C fan and, using a spoon, push down the centre of each pastry. Arrange 3 sliced pears over the tops of the tarts, crumble over 100g gorgonzola and 35g chopped walnuts. Drizzle with a little olive oil and bake for 10 minutes.
Serve with rocket leaves and drizzle balsamic vinegar over the tarts.