Prepare the Oven: Preheat the oven to 350°F (175°C). Grease a loaf pan (about 8×4 inches) or line it with parchment paper.
Mash the Bananas: Peel and mash the ripe bananas with a fork until smooth. Measure out about 1 1/2 cups and set aside.
Mix Wet Ingredients: In a large bowl, combine the mashed bananas and sugar until well mixed. Add the egg, vegetable oil, and vanilla extract, mixing thoroughly.
Combine Dry Ingredients: In a separate bowl, whisk together the flour, baking powder, and salt.
Combine Wet and Dry Ingredients: Gradually add the dry ingredients to the banana mixture, stirring until just combined. If using nuts, fold them into the batter at this stage.
Prepare the Decoration: Cut a banana lengthwise into two halves.
Pour the Batter: Pour the batter into the prepared loaf pan and smooth the surface.
Add the Decoration: Place the banana halves, cut side up, on top of the batter, gently pressing them into the batter. Sprinkle with sugar.
Bake: Bake in the preheated oven for about 60 minutes, until the top is golden and a toothpick inserted into the center comes out clean.
Cool the Bread: Remove the bread from the oven and let it cool in the pan for about 10 minutes. Then transfer to a wire rack to cool completely.