Preheat oven to 350 degrees and lighty spray a 9x13-inch baking dish with cooking spray. Line the baking dish with parchment paper, letting the paper come up the sides of the pan so that you can lift the bars out of the pan.
In a large bowl, whisk together the flour, confectioners' sugar, and salt. Add the butter cubes and use a pastry blender or two forks to cut it in until the mixture is crumbly.
Press mixture into the bottom of the prepared baking dish. Bake for 25 minutes or until golden around the edges.
In a large bowl, whisk together sugar, buttermilk, melted butter, eggs, lemon zest, lemon juice, cornmeal, flour, and vanilla. Pour over crust.
Bake for 30 minutes, or until filling is set.Cool completely and then use parchment paper to lift the cooked bars from the baking dish. Cut into squares.Store in the refrigerator.
Optional: Sift powdered sugar over bars before serving.
Notes
You can use unsalted butter and add an extra pinch of salt.