Cook the white onions long and slow on the lowest heat possible, so they become transparent and sweet. Don't use too strong a cheddar as it will mask the delicate onion flavour. Lancashire or Gloucester cheeses could be used instead. This is a perfect portable meal; you can either take it whole to your destination or slice it before you leave.
for the pastry
100g cold butter, cut into small pieces
180g plain flour
1 medium egg yolk
2-3tbsp water to mix
for the filling
3 medium onions, peeled and finely chopped
A good knob of butter
4 medium-sized spring onions, trimmed and finely chopped
2tbsp chopped chives
2 egg yolks
120ml double cream
Salt and freshly ground black pepper
100g medium farmhouse Cheddar grated
90g soft goat's cheese
First make the pastry. In a bowl, rub the flour into the butter with your fingers until it's breadcrumb-like. Add the egg yolk, Parmesan, a good pinch of salt and mix in enough water to form a stiff but workable dough.
Roll the pastry on a lightly floured table to 1/3cm thick and line a 16-20cm x 21/2-3cm deep flan ring (or a rectangular one about 30cm x 12cm) with it. Trim the edges then rest for 30 minutes. Pre-heat the oven to 200C/Gas mark 6.
Lay a circle of greaseproof paper on top of the pastry and weigh it down with baking beans, then bake for 15 minutes. Meanwhile gently cook the onions in the butter with a lid on for 5-6 minutes, stirring every so often, until soft. Stir in the spring onions, cook for another minute, remove from the heat, stir in the chives and leave to cool. Mix the eggs with the cream, milk and Cheddar and season. Remove the greaseproof paper and beans from the flan and spoon in the cooked onions. Pour in the egg mixture then break the goat's cheese into small pieces and dot around in the egg mix. Bake for 15-20 minutes until just set and lightly coloured. Remove and leave to cool. Serve with a green salad or the beets with orange.