In a large, shallow bowl (or plate with high edges), combine eggs, splash of milk and cinnamon. Whisk together until fully combined.
Cut the edges off the slices of bread then roll out each slice with a rolling pin.
Fill each flattened slice of bread with peanut butter then place banana slices in a single later at the edge (you can also mash the banana). Sprinkle with cinnamon if desired.
Starting from the banana side, roll the bread up tightly then dip into the egg/milk/cinnamon mixture.
Place a small amount of butter onto a preheated griddle or a pan that has been placed over medium heat. Spread butter all around to coat the surface then place roll-ups on. Cook roll-ups 1-2 minutes per side making sure you cook each side.
Remove, let cool for a few minutes and serve!