Preheat your oven to 375°F (190°C) and place the pie crust in a 9-inch pie dish. Using a fork, prick the bottom of the crust all over to prevent bubbling during baking. Bake for about 15 minutes or until golden around the edges. Remove from oven and set aside to cool slightly.
In a saucepan, whisk together 1 cup of sugar, cornstarch, and a pinch of salt. Slowly add the lemon juice, lemon zest, and melted butter, whisking continuously until smooth.
Cook the mixture over medium heat, stirring constantly. Continue until the mixture thickens and begins to bubble, about 5-7 minutes, with a glossy and smooth appearance. Remove from heat and let cool slightly.
Separate the egg whites into a clean, dry mixing bowl. Add cream of tartar, and beat with an electric mixer on high speed until soft peaks form. Gradually add the remaining 2 tablespoons of sugar while continuing to beat until stiff, glossy peaks are achieved.
Pour the slightly cooled lemon filling into the baked pie crust and spread evenly. Spoon or pipe the meringue over the filling, ensuring all edges are sealed to prevent shrinking during baking.
Bake the assembled pie on a baking sheet at 375°F (190°C) for about 10-12 minutes, or until the meringue turns golden brown. Keep an eye on it to ensure even coloring and prevent over-browning.
