Preheat oven to 325°F and grease a 9-inch springform pan.
Mix graham cracker crumbs and melted butter. Press into pan and bake for 10 minutes. Let cool.
Beat cream cheese and sugar until smooth. Add eggs one at a time, mixing well after each.
Add sour cream, heavy cream, vanilla, and lemon extract. Mix until smooth.
Pour mixture over crust. Bake in a water bath for 55-65 minutes. Cool and refrigerate overnight.
Once chilled, spread lemon curd over cheesecake.
In a clean bowl, beat egg whites with salt and cream of tartar. Gradually add sugar until stiff peaks form.
Pile meringue on top of lemon curd and broil for 1-2 minutes until lightly browned, or torch until golden.
Chill for at least 1 hour before serving.