In a small pan, heat 1 Tbsp butter over medium heat. Add banana and sugar and cook, mashing as the banana softens, until banana is soft and slightly caramelized, about 3-4 minutes.
Meanwhile, lay the slices of bread on a cutting board. Slice off the crusts and set aside. Using a rolling pin, roll out the slices of bread until about ¼” thick.
In a small bowl, beat together the egg, milk, and cinnamon.
Place 1-2 Tbsp of banana mixture on to the center of a slice of bread. Brush one side of the bread with the egg mixture and roll the other end over to seal. Continue filling the slices of bread and then set aside.
Place each roll into the egg mixture and turn to coat. Place on a place and repeat with the remaining rolls. Place crusts in the egg mixture and toss to coat. Remove and place on the plate.
Heat 2 Tbsp butter in a medium pan over medium heat. Once heated, add the French toast rolls and crusts. Cook on each side for about 2-3 minutes or until browned and crispy. Once all sides are toasted, remove and set on a plate.
Top with powdered sugar, if desired. Serve and enjoy!