Prepare the crust: Preheat the oven to 325°F (163°C). In a medium bowl, combine graham cracker crumbs, granulated sugar, and melted butter. Press into the bottom of a 9-inch springform pan and bake for 8-10 minutes. Let cool while preparing the filling.

Make the lemon cheesecake filling: Beat softened cream cheese and sugar until smooth. Add eggs, one at a time, beating well after each. Stir in vanilla extract, fresh lemon juice, lemon zest, and sour cream. Pour over the cooled crust.

Bake the cheesecake: Bake at 325°F (163°C) for 50-60 minutes, until the center is set but slightly jiggly. Let cool inside the oven with the door cracked for 1 hour, then refrigerate for at least 4 hours, or overnight.

Make the lemon curd: Whisk eggs, granulated sugar, lemon juice, and zest in a medium saucepan. Cook over medium heat, stirring constantly until thickened, about 8-10 minutes. Stir in softened butter until smooth. Cool before spreading over the cheesecake.

Prepare the meringue: Beat egg whites and cream of tartar until soft peaks form. Gradually add sugar and beat until stiff, glossy peaks form.

Assemble the cheesecake: Spread lemon curd over the chilled cheesecake, then top with the meringue. Spread it carefully, creating peaks and swirls.

Bake the meringue: Bake at 325°F (163°C) for 8-10 minutes, or until the meringue is golden brown.

Serve and enjoy: Let cool slightly before slicing and serving.