Preheat your oven to 325°F (160°C). Mix graham cracker crumbs, melted butter, and sugar until well combined. Press into a 9-inch springform pan. Bake for 10 minutes until golden. Cool completely.

In a large bowl, beat cream cheese and sugar until smooth. Add eggs one at a time, mixing well. Incorporate sour cream, lemon zest, lemon juice, and vanilla extract. Blend until fully combined.

Pour lemon filling over the cooled crust. Place in a larger baking dish filled with hot water to create a water bath. Bake for 50-60 minutes until edges are set, center jiggles slightly. Cool in the oven for 1 hour.

Refrigerate cheesecake for at least 4 hours or overnight.

Whisk egg yolks, sugar, lemon juice, and zest in a saucepan over low heat for 8-10 minutes until thickened. Stir in cold butter until melted. Pour over chilled cheesecake.

Beat egg whites with cream of tartar until soft peaks form. Gradually add granulated sugar, beating until stiff peaks form. Fold in vanilla extract.

Preheat oven to 350°F (175°C). Spread meringue over lemon curd, creating peaks. Bake for 10-15 minutes until meringue is golden brown. Monitor to prevent overcooking.

Cool at room temperature for 1 hour, then refrigerate. Garnish with lemon slices or berries if desired.