✓ Preheat oven to 375°F (190°C). Grease a 9-inch tart pan with butter or line it with parchment paper.

✓ In a large bowl, mix flour and powdered sugar until combined. Cut in cold cubed unsalted butter using a pastry cutter or your fingers until mixture resembles coarse crumbs. Add an egg yolk and 1 tablespoon of ice water; mix until dough comes together. If too dry, add more ice water one teaspoon at a time.

✓ On a floured surface, roll out the dough into a circle about 1/8-inch thick. Place it in the prepared tart pan, trimming excess edges with a knife.

✓ Use a fork to prick several holes in the bottom of the shell. Bake for 12-15 minutes or until lightly golden brown. Remove and let cool completely on a wire rack.

✓ In a medium saucepan, combine lemon juice, zest, sugar, and eggs. Whisk together over low heat. Cook for 5-8 minutes or until mixture thickens slightly, stirring frequently to prevent sticking.

✓ Pour lemon curd into cooled tart shell. Smooth surface with a spatula.

✓ In a clean bowl, beat egg whites and cream of tartar until frothy. Gradually add sugar in three stages, continuing to beat until stiff peaks form.

✓ Spoon meringue onto the lemon curd layer, leaving some space around edges for oven caramelization. Use a piping bag or spoon to create swirls if desired.

✓ Place tart on middle rack of oven and bake for 8-10 minutes or until meringue is lightly golden brown.