Preheat oven to 350 degrees. Use butter or cooking spray to grease the inside of a large (9 in x5 in) loaf pan.
Use an electric mixer to beat butter, sugar and brown sugar until lightened, about 2 minutes.
Beat in eggs, one at a time, scraping down sides as needed.
On low speed, mix in crushed bananas until well combined.
In a small bowl, stir together flour, salt, baking powder, and cinnamon. Gradually beat into banana mixture.
Pour half of batter into prepared pan. Drizzle 1.5 tbsp caramel sauce over batter and use a toothpick or fork to swirl it evenly over top of batter. Pour remaining half of batter into pan. Drizzle remaining 1.5 tbsp caramel sauce over top of batter, and again use toothpick or fork to evenly swirl it over top of batter.
Bake for 50-55 minutes, or until knife inserted into center of bread comes out with just crumbs.