In a small bowl, mix the granulated sugar and ground cinnamon together. Set aside.
Take each slice of bread and gently flatten it using a rolling pin.
Spread a thin layer of the cinnamon sugar mixture onto each slice of flattened bread.
Roll each slice tightly from one end to the other to form a roll. Pinch the ends to seal them.
In a mixing bowl, whisk together the eggs, milk, and vanilla extract until well combined.
Dip each roll-up in the egg mixture, making sure to coat all sides.
In a frying pan or skillet, melt the butter over medium heat.
Place the roll-ups seam side down in the skillet. Cook for about 2-3 minutes on each side or until golden brown.
Once cooked, remove from the skillet and sprinkle with any remaining cinnamon sugar mixture.
Serve warm, dusted with powdered sugar and drizzled with maple syrup if desired.