Whisk together eggs, milk, vanilla, cinnamon, and salt until throughly blended. (Alternatively, use an immersion blender to mix together). Pour into a shallow bowl wide enough for bread.
Set a large skillet over medium heat and melt about a tablespoon of butter. Working with one slice of bread at a time, dip bread into egg mixture. Turn to coat other side of bread. Allow any excess liquid to drain.
Cook bread on hot skillet until browned on one side, about 2 minutes. Before flipping, sprinkle two pinches of sugar on exposed side of bread. Flip and brown the other side, another 2 minutes. Repeat with remaining bread. Add additional butter to skillet as needed.