Steps
1. In a bowl, whisk together the egg, milk, vanilla extract, and cinnamon until well combined.
2. Spread dulce de leche on one slice of bread, then top with the second slice.
3. Heat a skillet over medium heat and add a little butter.
4. Dip the stuffed bread into the egg mixture, ensuring both sides are coated.
5. Place the bread in the skillet and cook until golden brown on both sides, about 3-4 minutes per side.
6. Remove from the skillet, dust with powdered sugar if desired, and serve warm.