Preheat oven to 350. Prepare 8x8” brownie tin with baking spray and paper.
Measure flour, baking powder, salt, and cinnamon and sift twice, set aside.
On a stand mixer fitted with the paddle attachment, cream butter and sugar until light and fluffy, 2-3 minutes. Add eggs one at a time, beating well to combine after each addition. Scrape mixing bowl and blend well.
Beat in bananas, then gently mix in sifted dry ingredients. Finish folding in off the mixer.
Pour in prepared baking tin and bake in bottom middle of oven till a skewer inserted in the middle comes clean, 25-30 minutes.
Cool and invert onto serving tray, brush with cognac butterscotch sauce while still warm and serve with fresh sliced bananas and crème fraiche.