In a small bowl, mix together the granulated sugar and cinnamon. Set aside.
In a medium bowl, whisk together the eggs, milk, and vanilla extract until well combined.
Flatten each slice of bread using a rolling pin. This will make it easier to roll up.
Sprinkle a generous amount of the cinnamon sugar mixture over one side of each flattened slice of bread.
Roll each slice of bread tightly from one end to the other, starting from the side with the cinnamon sugar.
Heat a large skillet over medium heat and add the butter. Once melted, dip each roll-up into the egg mixture, ensuring they are well coated.
Place the roll-ups seam-side down in the skillet and cook for about 2-3 minutes on each side, or until golden brown.
Remove from the skillet and immediately roll in the remaining cinnamon sugar mixture.
Serve warm, dusted with powdered sugar and drizzled with maple syrup if desired.