Heat oven to 450°. Prepare a cookie sheet by lining with parchment paper, silpat liner, or spray with cooking spray.
In a mixing bowl, combine the flour, cornmeal, sugar, baking powder, baking soda, and salt. Whisk together to break up any clumps.
In a smaller bowl (I use the same 2-cup glass measurer that I melted the butter in) combine the melted butter, sour cream, and milk. Whisk together until combined. Pour into the dry ingredients and gently stir together. Just stir until combined and no flour pockets remain in the dough.
Drop the dough (each biscuit is 1/4 cup) onto the prepared cookie sheet. You can use two large spoons, a cookie scoop, or a 1/4 cup measuring cup to drop the biscuit dough.
Bake for 12-14 minutes. Outside should be golden brown and the inside will be soft and fluffy. Just make sure to cook until the middle is no longer wet. Use a toothpick if you have to, to test the middle.
OPTIONAL TOPPING : Combine the melted butter and parsley in a small bowl. Immediately brush it on top of the biscuits after they are out of the oven. I usually don't do this, instead I serve them with butter & honey at the dinner table OR I will just brush them with melted butter.