Ingredients:

1 quantity tart pastry
1 ¾ oz. butter (3 tbs)
1 lbs 4 oz onions, finely sliced
2 tsp thyme leaves
3 eggs
1 ¼ c. heavy cream
½ c. grated Gruyere Cheese
grated nutmeg
salt and pepper

Preheat the oven to 350. Line a 9 inch fluted loose-based tart tin with the pastry. Line the pastry with crumpled greaseproof paper and baking beads (use dried beans or rice if you don't' have beads). Blind bake the pastry for 10 minutes, remove the paper and beads and bake for a further 3-5 minutes, or until the pastry is just cooked but still very pale.

Meanwhile, melt the butter in a small frying pan and cook the onion, stirring, for 10-15 minutes, or until tender and lightly browned. Cook the onion slowly to bring out the sweetness. Add the thyme leaves and stir well. Leave to cool. Whisk together the eggs and cream and add the cheese. Season with salt, pepper and nutmeg.

Spread the onion into the pastry shell and pour the egg mixture over the top. Bake for 35-40 minutes, or until golden brown. Leave in the tin for 5 minutes before serving.

Tart Pastry

Ingredients:

1 ¾ c. All-purpose Flour
pinch of salt
5 ½ oz. unsalted butter (about 9.6 tbs) chilled and diced
1 egg yolk

Sift the flour and salt into a large bowl, add the butter and rub in with your fingertips until the mixture resembles breadcrumbs. Add the egg yolk and a little cold water (about 2-3 teaspoons) and mix with the blade of a palette knife until the dough just starts to come together. Bring the dough together with your hands and shape into a ball. Wrap in plastic wrap and put in the fridge to rest for at least 30 minutes. (You can make the dough in a food processor, using the pulse button.)

Roll out the pastry into a circle on a lightly floured surface and use to line a tart tin, as directed in the recipe. Trim the edge and pinch up the pastry edge to make an even border raised slightly above the rim of the tin. Slide onto a baking tray and rest in the fridge for 10 minutes.