Preheat oven to 350°F and grease an 8.5 x 4.5 inch or a 9 x 5-inch loaf pan. Also line it with a strip of parchment paper along the bottom, making sure it comes up over the ends so you can use it as a handle to lift the loaf out once cooked.
Peel the bananas then add them to a large mixing bowl and mash them with a fork or masher until they are a pretty smooth puree.
Add the oil/nut butter, sugar, molasses, salt and optional cinnamon or cardamom, then beat well until smooth.
Add the flour and baking powder to the bowl and gently stir it all together. Do not over-mix. You want it so that it is just combined and you cannot see any dry flour throughout the mixture. Overmixing or beating it hard will affect the texture of the banana bread.
Pour/spoon the batter into your prepared pan. If you want to you can sprinkle the top with some granulated sugar for a nice crunchy texture, or add some banana slices for decoration.
Bake in the oven for around 50 minutes or until a tooth pick or skewer comes out clean when inserted through the middle.
Lift out of the pan, remove parchment paper and cool on a cooling rack.
NOTES
Store leftover banana bread in an airtight container for 5 to 6 days or freeze for up to 3 months.