Preheat oven to 350°F (177ºC). For a convection oven, reduce cooking temperature by 25ºF (15ºC). Spray a (9" x 5" or 23 x 13 cm) loaf pan with nonstick spray and place a sheet of parchment paper on the bottom.
Whisk all the dry ingredients (flour, baking powder, baking soda, salt, cinnamon, and allspice) together in a large bowl. Make a well in the center of the mixture.
Combine Nutella and honey in a small bowl and heat in the microwave until melted, (about 30 seconds) and cooled slightly.
Combine mashed banana, buttermilk, egg, and extracts in the medium bowl.
Add cooled Nutella-honey mixture in the medium bowl.
Add to flour mixture in the large bowl and stir just until combined.
Pour batter into the greased loaf pan and top with almonds and turbinado sugar.
Bake at 350°F (177ºC) for 50-60 minutes, rotating the pan halfway through. The bread is ready when an inserted skewer in the center comes out clean. Remove from oven and cool in the pan on a wire rack for 10 minutes, then remove from pans and cool completely.
Wrap the bread well and store at room temperature up to 2 days, or in the refrigerator up to 4 days. To freeze, wrap tightly in foil or freezer wrap.