
1 1/4 cups cake flour
3/4 cup sugar
1/2 cup chopped walnuts
1 teaspoon baking powder
1/2 teaspoon bicarbonate of soda
1/2 teaspoon ground cinnamon
1/2 teaspoon freshly grated nutmeg
1/4 teaspoon fine salt
1 cup smashed banana (2 to 3 small bananas)
1/2 cup vegetable oil, plus more for brushing waffle iron
1/2 cup sour cream
1 teaspoon pure vanilla extract
2 large eggs
Soft unsalted butter and icing sugar, for dusting, optional
Special equipment: waffle iron (preferably Belgian style)