1 cup (120 grams) unbleached all-purpose flour
1/2 cup (60 grams) whole wheat flour (I use and recommend King Arthur)
1 and 1/2 teaspoons instant espresso powder (such as Medalgia d'Oro)
1 teaspoon kosher sea salt
1 teaspoon baking soda
1/4 teaspoon baking powder
1/2 teaspoon ground cinnamon
1/4 teaspoon ground allspice
6 tablespoons unsalted butter, softened
3/4 cup granulated sugar
2 whole large eggs
1 teaspoon pure vanilla extract
1 cup (250 grams) mashed very ripe banana (about 4 dead bananas)
1/3 cup low-fat or whole milk
3 ounces chopped semisweet chocolate
demerara sugar, for sprinkling