Place flour on a work surface and make a well in the center.
Work butter and salt into the flour until combined but with visible butter lumps.
Mix in iced water gradually to form a rough dough.
Roll the dough into a ball, wrap in film, and chill for 20 minutes.
Roll dough into a 40x20cm rectangle, fold into three, and turn.
Repeat the folding and turning process once more.
Wrap the pastry and chill in the fridge for 30 minutes.
Roll into a 40x20cm rectangle, fold into three, and turn again.
Repeat the fold and turn for a total of four turns.
Wrap and chill the pastry for at least 30 minutes.
Blend rocket, garlic, pine nuts, and oil into a fine puree.
Preheat the oven to 200°C.
Roll pastry to 2mm thickness and cut into six 12cm discs.
Place pastry discs on a lined baking tray brushed with cold water.
Spread 10ml of pesto on each disc, leaving a 1cm border.
Top with mozzarella and tomatoes, drizzle with oil, and brush edges with egg yolk.
Bake for 12 to 15 minutes until the pastry is golden-brown.
Garnish with additional pesto and fresh basil leaves to serve.