Start by flattening each slice of bread with a rolling pin until thin.
In a small bowl, mix the blueberries with 1 tablespoon of sugar and set aside.
Place a spoonful of the blueberry mixture at one end of each flattened slice of bread. Roll the bread tightly around the blueberries.
In a shallow bowl, whisk together the eggs, milk, vanilla extract, cinnamon, and remaining sugar until well combined.
Heat a skillet over medium heat and melt 1 tablespoon of butter.
Dip each roll-up in the egg mixture, ensuring they are coated on all sides, then place them seam-side down in the skillet.
Cook for about 2-3 minutes on each side or until golden brown. Add more butter as needed for cooking.
Once cooked, remove from the skillet and dust with powdered sugar if desired. Serve warm.