- Preheat the oven to 200ºC fan oven/220ºC/gas 7.
- Heat the oil and butter in a large saucepan. Add the onions and fry gently, for about10 minutes, until they caremelise. Keep the onions moving to allow an even browning.
- Add the thyme, raisins, pine nuts and thyme to the pan and heat through.
- Cut the sheet of pastry into 6 squares. Using a muffin tin, place each piece of pastry into holes set apart. Let the excess pastry hang over the edges, does not need to be neat. Brush the edges with the beaten egg.
- Place a teaspoon of the red pesto in the bottom of each tart. Distribute the onion mix evenly between the tarts. Place slices of the Brie over the top.
- Place in the oven for 20 minutes. The cheese will be melted and the tarts nicely crunchy and browned.
- Serve with some salad.