Melt butter in a small bowl and let cool. Whisk together flour, cornmeal, ¼ C sugar, the baking powder, salt, and baking soda. In another bowl, whisk together buttermilk, milk and egg. Whisk wet ingredients into dry ingredients until just combined (mixture will be lumpy).

Heat a griddle or large nonstick skillet over medium heat. Toss blueberries with remaining 2 teaspoons of sugar. Brush griddle with melted butter. Spoon batter onto griddle ⅓ cup at a time. Sprinkle with sugared blueberries, about 2 tablespoons per pancake. Cook until edges are set, 3 to 4 minutes. Flip, and cook until golden brown, about 1-2 minutes. Repeat with remaining batter and blueberries, adding more butter to griddle as needed.