Mix the Dry Ingredients: In a mixing bowl, combine the all-purpose flour and powdered sugar until well incorporated.

Cut in the Butter: Add the cold, cubed unsalted butter and mix until it resembles coarse crumbs.

Incorporate the Egg Yolk: Stir in the large egg yolk and gradually add cold water until the dough starts to come together.

Chill the Dough: Shape the dough into a disk, wrap in plastic wrap, and refrigerate for at least 30 minutes.

Preheat the Oven: Preheat your oven to 350°F (175°C) while the dough chills.

Roll Out the Dough: On a floured surface, roll out the chilled dough to about 1/8 inch thick and fit into a tart pan.

Par-Bake the Crust: Line with parchment paper and bake for 15 minutes; then remove weights and bake for an additional 10 minutes.

Prepare the Passionfruit Filling: Whisk together fresh passionfruit juice, granulated sugar, and large eggs in a saucepan over medium heat.

Cook the Filling: Add butter and cook until it thickens without boiling, about 5-7 minutes.

Strain the Curd: Strain the mixture through a fine-mesh sieve and stir in the vanilla extract.

Cool and Set: Allow to cool slightly before pouring into the cooled tart shell and refrigerate to set for at least 1 hour.

Whip the Meringue: Beat egg whites with cream of tartar until soft peaks form.

Add Sugar Gradually: Gradually add granulated sugar, beating until stiff peaks form and meringue is glossy.

Top the Tart: Spread or pipe meringue over the passionfruit curd, creating peaks.

Toast the Meringue: Use a kitchen torch or broiler to toast the meringue until golden brown.

Slice and Serve: Allow to cool slightly before slicing and serving.