Cup of Yum
1. Zest both lemons. Juice ¼ cup of juice, about 1 lemon. Set aside.

For the Crust

Cup of Yum
1. In a medium bowl, stir together the flour, sugar, and salt. Use a pastry cutter or fork to cut in chilled butter until it reaches pea-sized chunks.
2. Gradually add in cold water, stirring each time until the dough can be pressed together. Form it into a disk, wrap in plastic wrap and refrigerate for at least 2 hours, or freeze for 30 minutes until chilled.
3. Preheat oven to 425°F.
4. Lightly flour the surface and use a rolling pin to roll a 12-inch circle. Line a 9-inch pie plate with the pastry.
5. Gently press into the pie plate and over the sides. Trim the edges and crimp as desired. Poke the bottom and the sides with the tines of a fork all over to help prevent puffing (or line pie crust with parchment and use pie weights if you have them).
6. Bake for 12-15 minutes or until the pie crust is baked through and light golden brown. Set aside while you make the filling.

For the Filling

1. In a medium saucepan, whisk together the sugar, water, corn starch, egg yolks, lemon juice and lemon zest.
2. Cook over medium to medium-high heat, whisking constantly until the mixture comes to a boil and thickens. It will be slightly thicker than pudding. This can take 10-15 minutes, but don't rush it. Once thickened, remove from heat and stir in butter.
3. Pour hot filling into the pie crust, set aside and prepare the meringue.

For the Meringue

1. Preheat the oven to 375°F.
2. In a small saucepan, whisk together the water and corn starch. Cook over medium heat until thickened and clear. Set aside but keep warm.
3. In the bowl of a stand mixer fitted with a whisk attachment, or a clean bowl with clean beaters, beat egg whites, vanilla and salt until soft peaks form.
4. Gradually add in the sugar, beating until stiff glossy peaks form.
5. Gradually add in the warm corn starch mixture, beating constantly, until completely incorporated and meringue is light and fluffy and holds stiff peaks.
6. Spread meringue onto hot pie filling (it's important that the filling is still hot!) and spread right to the edge of the pie crust. The meringue must touch the edges all the way around.
7. Bake at 375°F for 5-8 minutes or just until the tops of the meringue are light golden brown -- don't overbake.
8. Let rest on the counter on a wire rack for 1-2 hours, then refrigerate for 5-6 hours until chilled, or overnight.
9. Slice and serve.