Preheat the oven to 350 degrees Fahrenheit.
Place the two bananas cut in larger pieces into the food processor and puree them.
Dump in the remaining ingredients in the food processor except the banana cut into slices and 2 tablespoon of maple syrup.
Blitz until a smooth batter forms. Scrape the sides and bottom of the food processor with a spatula if necessary to ensure everything is mixed in.
Spray the bottom of an 8-inch cast iron skillet or cake pan with cooking spray. Pour in 1 to 2 tablespoon of maple syrup (use 1 tablespoon if you want a less sweet cake). Tilt the skillet or pan so the maple syrup coats the bottom.
Arrange the banana slices over the maple syrup in any pattern you want. This will form the top of the cake so make sure you try and make it look pretty.
Pour the cake batter over the banana slices and smooth the top with a spatula, if needed.
Place in the preheated oven and bake 25-30 minutes or until a toothpick in the center comes out clean.
Let the cake cool on a rack 30 minutes. Run a knife along the sides to loosen the cake from the pan.
Then, very carefully and using oven mitts, especially if you are handling a cast iron skillet, place a dish over the skillet or pan and flip it over quickly. This should unmold the cake.
Let the cake continue to cool (in the dish) on a rack for at least 30 more minutes. Serve warm or at room temperature.