Prepare Roll-Ups:
Using a rolling pin, flatten each slice of bread. Spread about 1 tablespoon of Nutella evenly over each slice. Roll up the bread tightly.

Make Egg Mixture:
In a shallow bowl, whisk together eggs, milk, vanilla extract, and cinnamon.

Dip Roll-Ups:
Dip each roll-up in the egg mixture, coating all sides.

Cook:
Heat butter or oil in a skillet over medium heat. Fry roll-ups, turning occasionally, until golden brown on all sides (about 2–3 minutes per side).

Serve:
Remove from skillet and dust with powdered sugar if desired. Serve warm.