Preheat the oven to 350 degrees F. Grease an 8x8-inch pan with extra butter and line with parchment paper, leaving enough paper to overhang on all sides. Set aside.
In a separate bowl, whisk together the milk, sour cream, and egg. Slowly whisk in the melted butter. Pour the wet ingredients into the dry ingredients and stir just until combined and there are no lumps, making sure not to overmix.
Pour the batter into the prepared pan and smooth the top with a rubber spatula. Bake in preheated 350-degree F oven for 20-30 minutes, or until a toothpick inserted into the center comes out clean. Place pan on a rack to cool and use overhanging parchment paper to remove from pan and slice.
Make It Ahead: Bake the corn bread and cool completely. Wrap cooled corn bread tightly in plastic wrap and place in a freezer baggie. Refrigerate for up to 4 days or freeze for up to 3 months. Defrost, if necessary, slice and toast.
Recipe adapted from Make It Ahead: A Barefoot Contessa Cookbook by Ina Garten