- 125g butter, diced
- 250g plain flour
- 1 egg, lightly beaten
- 3 large onions, cut into slices 2-3mm
- 75g butter
- 2 tablespoons olive oil
- 2 tablespoons plain flour
- 300ml double cream
- 3 eggs
- Rub the butter into the flour to create ‘breadcrumbs’ along with a generous pinch of salt. Add the egg, work to form a dough, you may need a tablespoon or two of cold water. Wrap in clingfilm and place in the fridge for an hour.
- Cook the onion with the butter and oil in a covered pan over the lowest heat for 45 minutes or until just coloured and soft. Take care to check frequently for the last 20 minutes or so as it can easily catch. Add a seasoning of salt and the flour and stir and cook for a further two minutes
- Preheat the oven to 150ºC/gas mark 2.
- Beat the cream and eggs together and, when the onions have cooled, slightly stir the cream mixture in.
- Roll the pastry out and line a 25cm tart tin. You’ll probably end up doing a lot of moulding with your fingers, which is fine, the dough is meant to be quite soft. Pour in the filling and bake for an hour or until set.
The key is in stewing the onions soft and long to draw out the sugars. Don’t let them colour and, if things become a little challenging, a few tablespoons of water should help them sauté rather than fry.