You will need (assuming you are going to make the pastry case and lemon curd lining yourself):-
The day before you make the tart you first need to make the pastry for the case. Take 4oz plain flour and 4oz self-raising flour and place into a large bowl. Cut 2oz butter and 2oz vegetable fat into ½" cubes and add to the bowl. Then using your finger tips rub the fats and flour together until there are no visible lumps of fat and the mixture looks like breadcrumbs. Slowly add water, dessert spoon at a time, each time thoroughly mixing the pastry with a wide knife. Enough water has been added if no pastry sticks to the sides, and if you scrunch the pastry together into a ball with your hands, the ball doesn't crumble to bits if you drop it into the bowl from 3" height. Too much water and the ball will stick to your hands. Take the ball of pastry and seal it in a plastic bag in the fridge overnight. Alternatively buy 12oz pre-prepared shortcrust pastry.
In this recipe lemon curd is used to line the inside of the pastry base. Bought is fine, but homemade is quite easy to make and is delicious. You can either make it on the day or beforehand. It will keep in a sealed container in the fridge for a week.
Take an approx. 2 pint (1200ml) glass bowl and find a saucepan into which the bowl is slightly too big to fit into the sides. If you have a Bon Marie, even better. Fill the pan/Bon Marie 1/3 with water and bring to a gentle boil. Put 3oz of caster sugar and the finely grated rind of a large unwaxed lemon (use the finest bit of a cheese grater, grate off the bright yellow skin but not the pith) into the bowl or inner Bon Marie pan. Place the bowl or inner Bon Marie pan into the larger pan of boiling water. In a separate bowl, beat two large eggs and the juice of the large lemon together then add to the contents of the container over the boiling water. Add 2oz butter, cut into ½" cubes, to the container then stir gently with a wooden spoon. Firstly the sugar will dissolve, then the butter, and then after about 5 minutes the mixture will begin to thicken. (You'll probably have to keep turning the heat down to stop the water boiling too much.) Keep stirring for another 3-5 minutes, until the curd thickens no further. Put the container containing the curd in the fridge for 30 minutes before using it in the tart.
Take the pastry (as pre-prepared above or bought) out of the fridge and leave at room temperature for 30 mins. Preheat the oven at 200(C/400(F/Gas mark 2. Take a 10" diameter, 1" deep enamel pie dish and grease the inside with butter. Once the pastry is ready, roll it out to about 14" diameter and press gently to cover the inside of the dish. Cut off the excess and press the rim into place with the back of a fork. Add 5 tablespoons of the lemon curd and spread gently all over the base and sides of the pastry case using a wide or palette knife.
Finely grate the rind of 2 large unwaxed lemons (use the finest bit of a cheese grater, grate off the bright yellow skin but not the pith) into a bowl, then add the juice of the 2 lemons to the bowl and put to one side. Weigh out 8oz self-raising flour and 2oz into another bowl and mix together with a spoon. Leave this bowl on one side too.
Take 6oz of caster sugar, and 6oz of butter cut into ½" cubes, and cream together with a mixer until light and fluffy. Crack 2 large eggs into a cup and beat them gently with a fork. Add the beaten eggs to the creamed sugar, a teaspoon at a time, still using the mixer. Now remove the mixer, and using a large wooden spoon, fold the flour/almond mixture into the butter/sugar/eggs in the mixer bowl, bit by bit. Try to do your best to incorporate everything, although the mixture does become very thick by the end so this is easier said than done. Now mix the previously prepared lemon juice and rind into the thick cake mix bit by bit. Once you've finished the mixture will have become a little easier to handle. Spoon the mixture into the pastry case lined with lemon curd and smooth with wide/palette knife. Then decorate with 2oz of whole blanched almonds. You can place them fairly closely, because the tart expands quite a bit when baked.
Place the tart in the centre of the oven at 400F/200C/Gas mark 6 for 15 minutes only, then reduce the heat to 300F, 150C/Gas mark 2 until the top of the tart is golden brown all over and the centre is not soft. This will take 30 - 45 minutes. The top of the tart always cracks - this cannot be avoided. The tart freezes well, and is best served hot with custard.