You will need a 20cm flan tin or pie dish, preferably metal.
- Put the Quaker Oats in a food processor and blitz for a few seconds until you get a fine powder. Add the plain flour and a pinch of salt. Pulse briefly to mix. Cut the butter and lard into cubes and add to the flour mixture. Process just until you obtain a mixture resembling fine breadcrumbs. Add the egg yolk and process briefly again. Then with the motor running on low, add just enough cold water to bring the mixture together (c. 1 tbsp). Tip out, kneed briefly, wrap in clingfilm and put in the fridge to rest for half an hour or so. (You will need to take the pastry out and allow to return to room temperature before rolling out.)
- Peel the onions, cut in half lengthways and slice finely into half rings. Heat olive oil in a heavy based saucepan, add the onions with a little salt, cover the pan and fry gently, stirring occasionally until the onions are soft and starting to caramelise (about 20 -30 minutes).
- Preheat the oven to 180° C. Roll out the pastry and line the tin/dish. Put greaseproof paper on the pastry, add baking beans and bake blind for 15 minutes. Remove tin from oven, take off paper and beans, and paint the inside of the pastry case with the egg white. Return to the oven for a further 5 minutes.
- Pile the onions into the pastry case and spread out evenly. Cut the camembert into thin wedges and arrange on top, pressing them into the onions. Whisk the egg and the milk together, add salt and pepper. Pour half over the onions, then put the flan on the oven shelf and top up until nearly full. The exact quantity required will depend on the volume of your flan/pie tin and how much onion and camembert you’re used. Bake for 20 -25 minutes or until the flan is mostly firm to the touch but with a slight wobble in the middle. Serve warm or at room temperature with a green salad.
This pastry is also nice used to make little tartlets. Use a shallow 12 tartlet tin, bake the tartlets blind then fill with caramelised onion and top with a thin wedge of camembert, (don’t bother with the egg and milk) then bake again for about 15 minutes. Great for serving as canapés.