In a shallow bowl, whisk together the eggs, milk, cinnamon, vanilla extract, and a pinch of salt. Heat a frying pan over medium heat and add a small amount of butter. Dip each slice of bread into the egg mixture, coating both sides, and let any excess drip off. Place the soaked bread in the hot pan and cook for 2–3 minutes on each side until golden brown and cooked through. Repeat with remaining slices, adding more butter as needed. Serve warm with syrup, berries, or a dusting of icing sugar.