Whisk the flour, cornmeal, sugar, baking powder, ½ teaspoon salt and 1 cup of the grated cheese in a large mixing bowl. In a separate mixing bowl, whisk 2 eggs, then whisk in the buttermilk and vegetable oil. Incorporate the wet ingredients into the dry ingredients and mix just until combined.
Preheat a waffle iron and coat with cooking spray. Pour some of the batter into the waffle iron and cook until golden brown, about 5 minutes. Transfer the waffles to a wire rack set on a baking sheet. Repeat with the remaining batter.
Meanwhile, whisk the remaining 8 eggs with the scallion in a large bowl. Melt the butter in a medium nonstick skillet over medium heat. Add the beaten eggs and gently stir with a rubber spatula until just set, about 5 minutes. Remove from the heat; cover to keep warm.
Just before serving, preheat the broiler to low. Scatter the remaining 1 cup grated cheese over the waffles and broil just until the cheese melts, about 1 minute. Top the waffles with the scrambled eggs.