1. Preheat oven to 200°C. Lightly grease a 24cm loose-bottom quiche tin.
2. Cut and join the pastry sheets so they completely line the tin with a small amount of pastry overhanging; prick the base with a fork. Place the tin on a rimless baking sheet. Line the pastry shell with greaseproof paper and fill with baking beans. Blind bake for 15 minutes.
3. While the pastry is cooking, sauté onions in olive oil over a medium heat until translucent. Add brown sugar, red wine vinegar and reduce until onions are soft and the sauce is sticky.
4. Remove paper and blind baking beans from the pastry shell. Trim any overhanging pastry and scatter the caramelised onions over the base. Add pine nuts and ½ the feta.
6. Whisk eggs and cream and season with salt & pepper. Pour into pastry shell, top with tomatoes and remaining feta. Return to oven and bake for 35 minutes or until golden and set. Cool in the tin for 5 minutes before serving.