Add all ingredient to a blender or food processor and blend until smooth. You may have to stop and scrape down the blender to ensure that the banana gets fully blended.
Pour batter into a 6 inch spring form pan lined with parchment paper. Cover with foil.
Bake for 50 minutes - 1 hour, until cooked, removing the foil after 20 minutes. You will know it is done being cooked when the edges are browned and the cake is not gooey. It will still be a little jiggly when taken out.
Let cake cool for 20 minutes sitting out in the pan. Then remove from the pan, add to a plate (leaving on the parchment paper) and refrigerate for at least 5 hours. I left mine overnight to set.
Add toppings, divide out and serve.
Notes
This makes 4-6 servings, depending on how big of a slice you want. For less calories just have a smaller slice, nutrition information is for ¼ of the cake.*Adjust to your sweetness preference. ¼ cup was plenty sweet enough for me but if you want sweeter use ⅓ cup.