Fill a measuring jug with water and ice, place in the fridge. Take out a piece of plastic wrap and place it near where you are working.
Take half of your butter and cut into thin slices, about ⅛ inch thick and then place in the fridge.
In a large bowl, whisk together the flour, salt and sugar.
Take the remaining butter and cut into ½ inch cubes. Toss the cubes of butter in the dry ingredients, making sure they’re all evenly coated. Use your fingers to smoosh the butter into the flour, you want to completely flatten the cubes and make them smaller until the biggest pieces of butter are about the size of a pea.
Take out the chilled butter slices and add them to the bowl, tossing to coat in the flour, then use your fingers to flatten the butter slices. You’ll now have a mixture of very small and slightly larger bits of butter.
Drizzle 5 tablespoons of your ice water into the flour (make sure not to have any ice fall in). Use your hands to toss the flour and butter. Continue tossing the mixture until it forms a shaggy mass. Knead it just a bit, and take out any large clumps of dough and place on to the plastic wrap. Continue drizzling ice water, a tablespoon at a time, and kneading the dough until just a couple of dry spots remain and you have one large piece of dough. Place on to the plastic wrap.
Form the dough into a disc, then wrap it tightly in the plastic wrap. Refrigerate for at least 2 hours.
Take it out of the fridge and let it sit for about 5-10 minutes (depending how cold your kitchen is) to make it easier to roll out. Place it on a lightly floured surface and roll the dough out into a rectangle. Fold the dough in thirds, then rewrap tightly in plastic. Refrigerate for at least another 30 minutes (or up to 2 days)
With an oven rack in the middle position, preheat your oven to 425°F/220°C.
Take the dough out of the fridge and let it come to room temperature for 5-10 minutes. Roll the dough out on a lightly floured surface until it is about an inch wider than your pie plate. I find it easiest to gently lift the dough and place it on to the plate, but you can also roll it up on to your rolling pin and then unroll it on to your pie plate.
Let the dough slump into the plate and press very firmly on to the bottom and the area where the side and the bottom of the pie plate meet - this is going to help it not slump when baking!
Tuck the overhang underneath, this is going to give you a thicker edge. Go back and use your hand and fingers to firmly press your dough into the pie plate. Crimp the edges as desired, crimping firmly into the pie plate is going to help it not shrink and hold its shape.
Place your pie plate in the freezer for 10 minutes. Take the pie out and use a fork to prick the bottom a few times - this will make the bottom not puff up as much when baking.
Line the inside of the pie dough with two pieces of foil, making an X shape, and be sure you have the foil hanging over the edges - this will make it easier to lift out after baking. You also want the overhanging foil to cover the crust so it doesn’t brown too much.
Fill the pie plate with your pie weights, dried beans or sugar. Bake on the middle shelf of your oven for 15-20 minutes. The edges should be a light golden colour. Quickly take the pie out and lift the foil and pie weights out. Reduce the temperature of the oven to 350°F/175°C and place the pie back in. Bake for another 10-12 minutes until golden brown. Remove from the oven and let cool completely.
Use a pastry brush to wash an egg wash (whisk an egg yolk with a splash of water and a pinch of salt) at the bottom of the pie, this will help seal the crust.
Make Lemon Filling
Preheat your oven to 375°F/190°C. Place your prebaked pie crust and place on a baking sheet.
In a jug, whisk together your egg yolks and then set aside. Keep your whites for your meringue.
In a medium nonreactive saucepan, whisk your cornstarch, sugar, salt, lemon zest, lemon juice, and water together. Place over medium heat and cook, whisking, until it begins to thicken and bubble. This will take about 4-5 minutes.
Take the pan off the heat and pour about 1 cup of the hot lemon mixture into your yolks, whisking the yolks vigorously so they don’t start to curdle. Pour this warm egg mixture back into your pan and place it over a low heat. Whisk constantly until it becomes thick and glossy, about 4-5 minutes.
Take the pan off the heat and add the butter, a piece at a time, whisking until it has completely melted.
Pour the filling into your cooled pie crust. Place a piece of plastic wrap on to the surface. Note, the curd is going to thicken a lot more because it is going to get cooked and then cools - so don’t worry if it isn’t as thick as you thought it would be!
Make Italian Meringue
Place your egg whites and cream of tartar into an incredibly clean stand mixer bowl and set to the side. Fit your stand mixer with the whisk attachment. You want to make sure there are no bits of egg yolk in the egg whites left, the egg yolk contains fat which will stop a meringue from forming.
In a small saucepan, stir your sugar and water together. Place it over medium heat, stirring constantly, until your sugar dissolves and it begins to bubble. Decrease the heat to your lowest setting.
Go to your mixer and beat the egg whites on medium-high speed until medium-soft peaks form. Stop the mixer. You don't want the peaks to be super stiff and pointing straight up, instead they should have a soft bend at the tip.
Go back to your saucepan and increase the heat, place a candy thermometer or instant read thermometer into the mixer and boil the syrup until it reaches 236°F/113°C degrees. Take it off the heat and pour the syrup into a glass measuring jug to stop the cooking process
Pour a small amount of this sugar syrup on your egg whites, then beat on high speed for 5 seconds. Stop the mixer and pour about a third of your syrup, then beat again on high for 5 seconds. Do this twice more. Beat on medium speed for 2 minutes, then add in your vanilla and pinch of salt and whisk once more.
Take the plastic wrap off your lemon filling and use a small offset spatula to cover the filling. Make sure your meringue topping is touching the crust all the way around the pie - this helps the meringue not to shrink. Use the back of a small spoon to create swoops and swirls.
Bake for 8-10 minutes at 375°F. The meringue should be golden brown. Remove it from the oven and let it cool for at least 1 hour, then place in the fridge for 3-4 hours before serving.
This is best eaten on the same day. To keep for another day, refrigerate it and tent the pie with foil
Notes
My recipes have been developed and tested in metric grams. I highly recommend using a weighing scale and measuring out your ingredients the metric way. I have provided a conversion to US cups but please note that I haven’t tested the recipe with this method. Just click on ‘US customary’ above the ingredients.Room Temperature: I make sure that all of my ingredients for the filling and topping are at room temperature before I start the recipe, so pull out all of the ingredients about 2 hours before you start baking. You want to keep the butter for the pie dough cold. Salt: If you don’t have kosher salt, halve the amount of salt called for in the recipe. 1 teaspoon kosher salt = ½ teaspoon fine salt.Butter: I use European style butter, like Kerry Gold, in my recipes.Making Ahead: You can make the pie dough up to 2 days ahead. Storage: This is best eaten on the day of making, but you can tent the meringue and store in the fridge for another day or two.