Step 1: Make the Crust
Preheat your oven to 325°F (165°C).
In a bowl, mix graham cracker crumbs, sugar, and melted butter until combined.
Press the mixture firmly into the bottom of a 9-inch springform pan.
Bake for 8-10 minutes, then set aside to cool.

Step 2: Make the Cheesecake Filling
In a large bowl, beat the cream cheese and sugar until smooth and creamy.
Add eggs one at a time, beating after each addition.
Mix in vanilla extract, sour cream, lemon juice, and lemon zest until well combined.
Pour the filling over the cooled crust.

Step 3: Bake the Cheesecake
Place the cheesecake in the oven and bake for 50-60 minutes, or until the edges are set but the center still jiggles slightly.
Turn off the oven, crack the door open, and let the cheesecake cool in the oven for 1 hour.
Remove and refrigerate for at least 4 hours or overnight.

Step 4: Make the Lemon Curd
In a medium saucepan over medium heat, whisk together lemon juice, lemon zest, sugar, and egg yolks.
Cook, whisking constantly, until the mixture thickens (about 5-7 minutes).
Remove from heat and whisk in the butter until smooth.
Let cool completely, then spread the lemon curd evenly over the chilled cheesecake.

Step 5: Make the Meringue
In a clean bowl, beat the egg whites and cream of tartar on medium speed until soft peaks form.
Gradually add sugar and continue beating until stiff, glossy peaks form.
Beat in vanilla extract.

Step 6: Assemble and Toast
Spoon the meringue over the lemon curd layer, spreading to the edges to seal.
Use the back of a spoon to create swirls in the meringue.
Toast the meringue with a kitchen torch until golden brown, or place under the broiler for 1-2 minutes, watching closely.

Step 7: Chill and Serve
Refrigerate the cheesecake for at least 1 hour before slicing.
Slice with a clean, hot knife for perfect pieces and serve chilled.