Mix vanilla wafer crumbs, butter, sugar, and salt until combined. Press into the bottom and up the sides of a 9-inch fluted tart pan with a removable bottom. Refrigerate about 15 minutes, or until firm.
Preheat oven to 350°. Place tart pan on a rimmed baking sheet. Bake 12 minutes, or until crust is golden. Let cool slightly.
Reduce oven temperature to 325°.
Mix both sugars, cornmeal, and salt. Break apart any clumps. Whisk in eggs, egg yolk, and vanilla. Whisk in butter until smooth. Pour filling into tart shell.
Bake 35-40 minutes, or until top is dark golden brown and the edge is set but the center is still just a bit wobbly.
Cool on wire rack 15 minutes. Refrigerate until completely cooled, 2 hours up to 1 day. Unmold and serve.