Weigh or lightly spoon flours into dry measuring cups; level with a knife. Combine flours, flaxseed, and next 4 ingredients in a medium bowl, stirring with a whisk.
Combine milk, butter, and eggs, stirring with a whisk; add milk mixture to flour mixture, stirring until blended. Fold in mashed banana.
Preheat waffle iron. Coat waffle iron with cooking spray.
Spoon about 1/4 cup batter per 4-inch waffle onto hot waffle iron, spreading batter evenly to edges. Cook 3 to 4 minutes or until steaming stops; repeat procedure with remaining batter.
Young Chefs can:
Peel banana
Help add dry measured ingredients to mixing bowl
Older Chefs can:
Mash banana
Crack eggs
Had a little trouble finding buckwheat flour in my area (they were all pancake mixes), but it was worth it. These waffles are delicous!