Blueberry Lemon Corn Muffins

Preheat oven to 375°F. and line six 1/3-cup muffin cups with paper liners. Melt butter and cool. Into a large bowl sift together flour and baking powder and whisk in cornmeal, 1/2 cup sugar, lemon zest, and a generous pinch salt. In a bowl whisk together melted butter, milk, and yolks and add to flour mixture with half of blueberries, gently stirring until just combined. Divide batter evenly among cups (batter will fill cups) and press remaining blueberries into tops of muffins. Sprinkle tops of muffins evenly with remaining tablespoon sugar. Bake muffins in middle of oven about 15 minutes, or until tops are golden and a tester comes out clean. Remove muffins from cups and cool on a rack. Muffins keep in an airtight container at room temperature 2 days.