This is one of those things I made almost by accident. I started off making a slice of some sort, didn't have the right tin for it, so used a different tin, changed the base because it didn't taste nice as raw dough, and added more lemon to the topping because we like lemon.
It's quick and easy to prepare with no fiddly 'rubbing in' of butter, as I've always found the addition of olive oil to be a pretty reliable substitute in many baked goods. Make sure you use the light olive oil, as in lighter flavour. I've made it with stronger flavoured olive oil, and the result is still lovely, but there's a very very faint olive oil flavour to the base. You could also try other oils such as Macadamia, Avocado, or Hazelnut and I think you'd get a lovely flavour too.
Needless to say, you can make this with normal flour as well, but the result may differ slightly.
This turns out beautifully with a really 'short' shortcrust style base, and a delectable lemon custardy, lemon curd like topping.
So for the base, you need:
2 cups gluten free plain flour (I just use a commercial one)
1 cup icing sugar (confectioners sugar)
1 teaspoon vanilla essence
1/2 cup olive oil, with up to another 1/4 cup if required
For the topping, you'll also need:
2 cups caster sugar
2 tablespoons gluten free plain flour
Juice of one lemon
To bake your tart, you'll need a flan dish, or springform cake tin. I use my largest springform tin, which has a diameter of 9-10 inches or 23-25 cms.
Preheat your oven to 180C.
Line the tin or pie dish with silicone baking paper.
Put the ingredients for the base into a mixing bowl and combine, using just half a cup of the oil to start. For some reason, the amount of oil required seems to vary sometimes, and I can only put this down to nuances in the gluten free flour blend. Mix with a spoon initially, then use clean hands to bring the dough together. It should look like a cookie dough or pastry dough, with a similar consistency, so if you need a little more oil, add a tablespoon at a time to achieve that.
Press the dough into the base of the tin or dish, spreading it with your fingertips and easing it to cover the base of your dish or tin completely. The back of a spoon, heated briefly under running hot water, and dried, can help with smoothing and spreading the dough evenly.
Bake this for 20-40 minutes. The time variation is dictated by your oven and the size of the dish. So check it after 20 minutes, then every five after that. It needs to be golden at the edges fading to a paler cream in the centre. A touch test will be unreliable as it will only crisp upon cooling, so it's a bit of a case of 'if it looks right, it is right'.
While the base is baking, combine the ingredients for the mouthwatering, curd-like topping. Whisk it all together well, and once the base is baked to your liking, pour the topping over the base, and return it to the oven for 20-25 minutes or until it's firm in the middle.
Remove it from the oven, and allow it to cool slightly before serving or storing.
This is equally lovely served hot or cold, with either cream, icecream or greek yoghurt drizzled with honey, on the side.