Combine the sugar, cinnamon, 3 tablespoons of butter, and water in a small saucepan over medium heat.

Add the apple slices to the pan and stir gently to coat them in the mixture.

Simmer the apples for about 10 minutes or until they are tender and the liquid has reduced into a thick syrup.

Whisk the eggs, milk, and salt together in a shallow dish until well combined.

Melt 2 tablespoons of butter in a large skillet or griddle over medium-high heat.

Dip each slice of bread into the egg mixture, turning quickly to coat both sides without letting the bread become soggy.

Place the bread in the hot skillet and cook for 2 minutes per side until golden brown, working in batches and adding the remaining butter as needed.

Serve the warm French toast immediately, spooning the cinnamon apple mixture and syrup generously over the top.