Adjust oven rack to middle position and preheat to 400˚F. Butter an 8-inch square baking pan. Cut each cranberry in half (do not use food processor as you don't want purée). Place cranberries in a large bowl with confectioners' sugar and toss to coat.

Combine flour, cornmeal, sugar, baking powder, and salt; stir into cranberries.

Warm the milk slightly in the microwave (this will keep the melted butter from hardening; don't get it hot enough to cook the egg); whisk in egg and melted butter. Pour the liquid over the cranberry/cornmeal mixture and fold together gently but thoroughly. Pour batter into prepared pan and bake until golden and a toothpick inserted in the center comes out clean, 20 to 35 minutes (depending on your oven).

Cut into squares and serve warm or allow to cool in pan on a wire rack.