Spread 1/2 to 1 tablespoon of peanut butter on 3 of the slices of bread. Then divide the sliced bananas evenly between the 3 pieces of bread, laying them in one thin layer atop the peanut butter. Top with the other slice of bread. Set aside.
Mix the eggs, milk, vanilla, and cinnamon. Dip each sandwich into the egg mixture to coat. Set aside.
Heat a large pan with the canola oil in it over medium heat. When hot, add the dipped sandwiches to the pan. Brown on one side. Then flip and reduce heat to low. Continue to look until the second side is browned and the inside is slightly melted and gooey. Serve right away with pure maple syrup.