Ingredients
Method
1.Heat oil in large frying pan, cook onion and leek, stirring, about 15 minutes or until mixture starts to caramelise. Stir in thyme, cool.
2.Meanwhile, combine cheeses and egg yolk in small bowl.
3.Preheat oven to 200°C (180°C fan forced). Oil two oven trays, line with baking paper.
4.Using 20cm (8-inch) plate as a guide, cut one round from each pastry sheet, place two rounds on each tray. Divide ricotta mixture among rounds, leaving 4cm (1½-inch) border around edges.
5.Divide leek mixture over rounds. Turn border of each tart up around filling, brush upturned edges with egg white.
6.Bake tarts about 35 minutes or until pastry is browned lightly.