To make the corn purée, start by melting the butter, then add the corn, and cook the mixture until the butter is boiling and the corn starts to take on a golden color. Blend the mixture in a blender until smooth, then cool it down over an ice bath or in the fridge.
Mix together the flour, baking powder, baking soda, maple sugar, raw honey, and white miso paste. In a separate bowl, mix the buttermilk with the cooled corn purée and the eggs, then add to the dry ingredients. Mix to combine.
Pour the batter into the baking dish, cover with aluminum foil, and bake at 375 degrees F for 20 minutes. Remove the aluminum foil and continue to bake for an additional 20 to 25 minutes, or until the cornbread is done.