Preheat the oven to 350 degrees
Grease a 9 x 13 x 2-inch baking pan
Combine the flour, cornmeal, sugar, baking powder, and salt in a large bowl
In separate bowl, combine the milk, eggs, and butter
Stir the wet ingredients into the dry until most of the lumps are dissolved
Mix in 2 cups of the grated Cheddar, the scallions and jalapenos, and allow the mixture to sit at room temperature for 20 minutes
Pour the batter into the prepared pan, smooth the top, and sprinkle with the remaining grated Cheddar and extra chopped scallions
Bake for 30 to 35 minutes, or until a toothpick comes out clean
Serve warm or at room temperature