Banana Waffles with Pecans

1/2 cup pecans
1 1/2 cups all-purpose flour
1/2 cup yellow cornmeal
1 tablespoon baking powder
1/4 teaspoon salt
1 1/4 cups milk
1 1/2 sticks unsalted butter, melted
3 large eggs, separated
2 large ripe bananas, quartered lengthwise and cut into 1/2-inch pieces
1/4 cup sugar
maple syrup, for serving

Preheat the oven to 350 degrees F. Spread the pecans in a pie plate and bake for 10 minutes, or until golden. Let cool, then coarsely chop. Lower the oven temperature to 225 degrees F.
Preheat a waffle iron. In a large bowl, whisk the flour with the cornmeal, baking powder and salt. In a small bowl, combine the milk, melted butter and egg yolks. Stir the liquid into the dry ingredients just until moistened; lumps are okay. Fold the bananas into the batter.
In a clean bowl, beat the egg whites at medium speed until frothy. Increase the speed to high and beat until firm peaks form. Add the sugar and beat until the whites are stiff and glossy. Fold the whites into the batter until no streaks remain.
Oil or butter the waffle iron. Pour 1 1/4 cups of batter into the iron and bake until the waffle is golden, about 6 minutes, depending on the iron. Transfer the waffle to an oven rack to keep warm. Continue to cook the remaining batter in 3 batches. (There should be no need to regrease the iron between waffles.) Separate the waffles and serve with the toasted pecans and maple syrup