Preheat oven to 425° F. Butter an 8X8 metal or glass baking pan.
In a medium bowl whisk flour, cornmeal, sugar, baking powder, baking soda, nutmeg and salt. In another medium bowl — lightly beat eggs, then add buttermilk, melted butter, vanilla and zest.
Add wet ingredients into the dry and stir until the batter comes together but isn't over mixed. Pour into the prepared pan, then level batter with a knife or offset spatula.
Place on the center rack and bake for 18-22 minutes or until the top begins to brown, edges start to pull from the side, and a center toothpick comes out clean. Let stand 5 minutes on a wire rack, then serve warm or let cool further.