Batter: Place flour, salt and the water in a large mixing bowl. Whisk batter until a smooth batter is formed similar to cream. Rest at room temperature for 1 hours.
Heat a large crepe pan or frypan over high heat. Brush with a little butter. Pour in just enough batter to cover the pan, and rotate quickly using a circular motion to create a thin galette. When the edges of the crepe begin to peal away from the edge flip the crepe over.
Reduce heat to medium and crack an egg into pan, then spread the egg white across the surface of the galette. Top with a piece of ham, and scatter evenly with cheese. Cook for 2 minutes.
Fold the four edges towards the middle of the galette, making an envelope shape. Transfer to a serving platter. Brush with extra butter and serve.
Repeat with remaining batter, eggs and ham.