Preheat the oven to 350ºF (180ºC). Grease and flour a 12-serving muffin pan*.
In a large bowl, whisk together the flour, sugar, cornmeal, baking powder and salt.
In a medium bowl, whisk together the eggs, sour cream, oil, butter, vanilla and lemon zest until smooth.
Stir the wet ingredients into the dry ingredients until combined. Don’t over mix. A few lumps are okay. Fold in the blueberries.
Fill the muffin cups half full. Bake until the tops of the cakes are light golden, the tops are springy and a toothpick inserted into the center of the cakes comes out clean, about 14-16 minutes.
Cool the cakes in the pan for 5 minutes, then remove them from the pan and place them upside down on a cooling rack. Top the cooled cakes with Honey Butter Icing.
Honey Butter Icing
In a medium bowl, whisk together the powdered sugar, butter, honey, salt and 1 tablespoon of milk. Add additional milk as needed to achieve your desired consistency. Whisk until smooth.