No. 1 | Preheat your oven to 350°. Grease a 9 x 9 cake pan with butter.
No. 2 | Place a pan on medium heat and add ¼ cup butter and ½ cup of brown sugar. Cook, stirring often, until the sugar dissolves and the mixer begins to bubble, about 3 minutes. Pour the caramel into the greased cake pan, making an even layer along the bottom of the pan. Place the banana halves in the caramel, cut side down.
No. 3 | Sift the flour, cocoa, baking powder, baking soda, cinnamon and salt into a medium sized bowl and set aside. In the bowl of a stand mixer, beat the ⅓ cup butter, ½ cup packed brown sugar and egg until light and fluffy. Stir in the mashed banana and vanilla.
No. 4 | Add ½ the dry ingredients to the wet, and mix until combined. Stir in half the sour cream, then the rest of the dry ingredients and finish by mixing in the rest of the sour cream.
No. 5 | Pour the batter on top of the bananas in the cake pan and spread it out evenly.
No. 6 | Place the cake pan in the oven to bake for 40 minutes. Test the doneness by inserting a knife in the centre and ensuring it comes out clean. Allow the cake to cool for at least 10 minutes, but no more than 20 minutes, before turning it out onto a plate.
No. 7 | Serve warm with a scoop of ice cream.