Preheat oven to 350°F.
Line a loaf pan with parchment paper. Grease with melted butter or cooking spray.
In a large bowl, mash bananas with a fork. (If your bananas are still firm, microwave them for 30-60 seconds to soften them.)
When bananas are mashed, add 1/4 cup sugar, vegetable oil, corn syrup, egg and vanilla extract. Mix well.
In a medium bowl, add flour, corn starch, baking powder, salt and baking soda. Mix well with a whisk.
Slowly mix flour mixture in with wet ingredients in the larger bowl until just combined.
Fold in the walnuts. (Your mixture should look like a thick cake batter.)
In a small bowl, add cinnamon swirl ingredients, 1/4 cup sugar and ground cinnamon. Mix well and set aside.
Using a spatula, spread 1/3 of the batter in the bottom of the loaf tin.
Then spread 1/2 of cinnamon sugar..
Spread the next 1/3 of batter on top and add the remaining cinnamon sugar.
Spread the last 1/3 of the batter on top.
Create the swirl - Use a butter knife to cut the batter with a figure-eight motion.
Place pan in preheated oven on the middle rack and bake for 40 - 50 minutes. Insert a toothpick in the center of the bread to check for doneness. When the toothpick comes out cleanly, the bread is fully baked.
Tip bread out onto a wire rack to let cool for about 10 minutes before slicing.