Step 1

Preheat oven to 200°C. Oil two 12-hole (2-tbsp/40ml) deep flat-based patty pans.

Step 2

In a large frying pan, heat oil and butter; cook leek, stirring, about 5 minutes or until leek softens. Add garlic, sugar and vinegar; cook, stirring, about 8 minutes or until leek caramelises.

Step 3

Cut eight squares from each pastry sheet; press one pastry square into each pan hole. Spoon leek mixture into pastry cases.

Step 4

Cut cheese into 24 pieces. Place a piece of cheese on each tartlet.

Step 5

Bake tartlets about 20 minutes. Serve tartlets topped with thyme.