Creating the perfect Lemon Meringue Tart is easier than you might think. Follow these simple steps:

1. Prepare the crust: In a medium bowl, combine flour and powdered sugar. Cut in the softened butter until the mixture resembles coarse crumbs. Add the egg yolk and cold water as needed to form a dough. Press the dough into a tart pan and refrigerate for 30 minutes.

1. Preheat the oven: Set your oven to 350°F (175°C).

1. Bake the crust: Once chilled, bake the crust for 15-20 minutes until lightly golden. Remove from the oven and let it cool completely.

1. Make the lemon filling: In a saucepan, whisk together the sugar, cornstarch, and salt. Slowly add water, constantly stirring over medium heat. Bring to a boil and cook until thickened.

1. Combine with egg yolks: Gradually whisk some of the hot mixture into the beaten egg yolks to temper them. Pour it back into the saucepan and cook for another minute. Remove from heat and add lemon juice, lemon zest, and butter, mixing until smooth.

1. Fill the crust: Pour the lemon filling into the cooled tart shell, spreading it evenly.

1. Prepare the meringue: In a clean bowl, beat the egg whites and cream of tartar until soft peaks form. Gradually add sugar while continuing to beat until stiff peaks form.

1. Top the tart: Spread the meringue over the lemon filling, making sure to cover it completely and create peaks.

1. Bake the meringue: Place the tart in the oven and bake for 8-10 minutes, or until the meringue is lightly browned.

1. Cool and serve: Allow the tart to cool at room temperature for at least 30 minutes before slicing and serving.