Banana Waffles with Nutella

Name: Banana Waffles with Nutella
Ingredients: 2 cups all-purpose flour; 4 tablespoons sugar; 2 teaspoons baking powder; 2 teaspoons kosher salt; Pinch of ground cinnamon; Pinch of freshly grated nutmeg; 4 large eggs, separated; 2 cups whole milk; 4 ripe bananas , mashed; ¾ cup unsalted butter, melted and cooled; 1 cup Nutella