Preheat oven to 325°F (163°C). Mix graham cracker crumbs with melted butter until fully coated. Press into the bottom of a greased springform pan. Set aside.
Beat cream cheese and sugar until smooth. Add eggs one at a time, mixing well after each. Stir in vanilla, lemon juice, zest, sour cream, and a pinch of salt. Mix until creamy.
Pour filling over crust and tap the pan to release air bubbles. Bake for 45–50 minutes, until edges are set and the center is slightly jiggly. Cool completely.
Whisk lemon juice, sugar, and egg yolks in a saucepan. Add butter and cook over medium heat, stirring constantly, until thick (about 5–7 minutes). Cool completely.
Once cheesecake is cool, spread the cooled lemon curd evenly on top. Chill for 30 minutes.
Beat egg whites, sugar, and cream of tartar on high until stiff, glossy peaks form (5–7 minutes).
Spoon meringue over the lemon curd, creating swirls. Bake at 325°F for 15 minutes, until meringue is golden brown. Cool completely, then chill for at least 4 hours or overnight before serving.