Make the Crust:

1. Preheat your oven to 325°F (163°C). Line a 12-cup muffin tin with cupcake liners.
2. In a small bowl, combine graham cracker crumbs, sugar, and melted butter. Mix until the crumbs are evenly coated.
3. Spoon about 1 tablespoon of the mixture into each liner and press firmly to form a crust. Bake for 5 minutes, then set aside to cool.

Make the Cheesecake Filling:

1. In a medium bowl, beat the cream cheese and sugar until smooth.
2. Add the egg, vanilla extract, lemon juice, and zest. Mix until fully combined.
3. Spoon the filling evenly over the crusts, filling each liner about ¾ full.
4. Bake for 15-18 minutes, or until the centers are set. Let cool completely in the pan, then refrigerate for at least 1 hour.

Make the Lemon Curd:

1. In a small saucepan, whisk together egg yolks, sugar, and lemon juice. Cook over medium heat, stirring constantly, until thickened (about 5-7 minutes).
2. Remove from heat and stir in the butter until smooth. Let cool completely before using.

Make the Meringue:

1. In a clean bowl, beat egg whites and cream of tartar on medium speed until soft peaks form. Gradually add the sugar, 1 tablespoon at a time, beating on high speed until stiff, glossy peaks form.

Assemble the Cheesecakes:

1. Spoon a small dollop of lemon curd onto each chilled cheesecake.
2. Pipe or spoon the meringue on top of the lemon curd.

Toast the Meringue:

1. Use a kitchen torch to toast the meringue until golden brown. Alternatively, place the cheesecakes under a broiler for 1-2 minutes, watching closely to avoid burning.

Serve:

1. Remove the cheesecakes from the liners and serve chilled.