In a medium mixing bowl mash 4 of the bananas, reserving one, making sure to leave them slightly lumpy for texture. Set the mixture aside.
In the bowl of a stand mixer, beat the butter, granulated sugar and brown sugar on medium-high speed until light and fluffy, about 3 minutes. Add the eggs and the vanilla, beating well after each addition. Add the bananas and mix until just combined, being careful not to over-mix.
In a medium mixing bowl, sift together the flour, baking powder, baking soda, salt and cardamom. Slowly add the flour mixture to the batter and mix until just combined.
Fold in the chocolate chips with a wooden spoon and pour into a greased and floured 1½-pound loaf pan. Slice the remaining banana in half lengthwise and arrange on the top of the bread for garnish.
Bake until cooked through, and a toothpick inserted into the center of the bread comes out clean, about 60 minutes. Transfer the pan to a cooling rack and allow it to cool.
Cut the bread into 1-inch thick slices and serve buttered.
Notes
*Note: If you don’t have over-ripe bananas on hand, you can quickly ripen bananas by baking them in the peel on a baking sheet at 250ºF for 15 minutes then cool.