Heat oven to 400°F. Spray a 9x5 loaf pan with baking spray.

In a large bowl, mix flours, baking powder, baking soda, salt, espresso powder, ½ cup each of the nuts and chocolate chips, reserving the rest to top the bread. Whisk and set aside.

In another bowl, mix melted butter, brown sugar, eggs, mashed bananas, vanilla, and buttermilk. Whisk to combine.

Pour the wet mixture into the dry mixture. Use a spatula to mix just until combined. Don't overmix.

Pour batter into the sprayed loaf pan. Place banana slices on top of the batter, then brush with lemon juice to prevent browning.

Sprinkle the remaining nuts and chocolate chips in between the banana slices.

Bake at 400°F for 10 minutes. Then reduce heat to 350°F and continue baking for 30 more minutes, or until a toothpick inserted into the center of the loaf comes out clean.

Cool in the pan for 5 minutes, then remove and place on a wire rack to cool completely before slicing. Dust with powdered sugar, if desired.