Preheat the oven to 375°F (190°C).

Prepare the crust by whisking together flour, confectioners' sugar, and salt, then add cold butter and work it into the flour mixture.

Press the mixture into the bottom and up the sides of a 9-inch tart pan with a removable bottom.

Bake the crust for 20-25 minutes, or until lightly golden, then let it cool completely.

Prepare the filling by whisking together egg yolks, granulated sugar, lemon juice, and lemon zest.

Add melted butter to the egg yolk mixture and whisk until smooth.

Pour the filling into the cooled pie crust and bake for 15-20 minutes, or until the filling is set.

Make the meringue by beating egg whites and cream of tartar until stiff peaks form.

Spread the meringue over the filling and bake for an additional 10-15 minutes, or until the meringue is golden brown.

Let the pie cool to room temperature, then refrigerate for at least 2 hours before serving.