1. Whirl buttermilk, egg, sugar, and corn kernels in a blender until almost smooth. Measure cornmeal into a medium bowl; stir in buttermilk mixture. Let soak while proceeding.
2. Line an 8X8 inch baking pan with foil and coat with nonstick spray or butter.
3. Preheat oven to 400 F
4. Stir flour with baking powder, baking soda, and salt. Make a well; pour in wet mixture. Stir slightly, just wetting some of the flour mixture. Pour in melted butter; stir until all flour mixture is moistened. Batter is thick and not smooth. Turn into prepared pan; roughly level top.
5. Bake in centre of oven for 25-30 minutes or until lightly browned. Cool on a cooling rack for 5 minutes; then lift out of pan using foil edges. Loosen sides and peel off foil. Finish cooling cornbread on rack. Serve warm or at room temperature - cut into squares.
A double recipe fits into a 9X13 pan and needs 35-40 minutes in the oven.