Preheat oven to 350 degrees. Grease a 8 ½ x 4 ½ inch loaf pan.
In a small saucepan add 3 tbsp butter and brown sugar. Gently heat over medium until the butter melts. Stir to combine.
Pour into the prepared loaf pan and add the sliced banana in a single layer slightly overlapping. Set aside.
Using a hand mixer cream butter and sugar in a bowl. Add eggs one at a time and mix.
In a separate bowl whisk together the flour, baking soda, salt and cinnamon. Add the mashed banana to the creamed sugar and beat until incorporated. Add the dry ingredients and mix until just combined.
Pour the batter in the loaf pan.
Bake on a parchment lined sheet tray for 55-60 minutes until a toothpick inserted into the cake comes out clean.
Allow banana bread to rest for 10 minutes before inverting on to a plate. Allow to cool completely before slicing.