Let's cook.
In a large bowl, whisk together the flour, eggs, milk, water, and salt until smooth. Stir in the 2 tablespoons of melted butter.
Heat a lightly buttered 8-inch non-stick skillet or crepe pan over medium heat. Pour about 1/4 cup of batter into the center of the pan, tilting and swirling to coat the bottom evenly.
Cook for 1-2 minutes, or until the edges are lightly golden and the crepe can be easily lifted. Flip the crepe and cook for another 30-60 seconds.
Remove the cooked crepe from the pan and place it on a plate. Repeat with the remaining batter, stacking the crepes as you go.
Once all crepes are cooked, return one crepe to the warm skillet. Place 2 slices of ham and about 1/4 cup of shredded Gruyère cheese on one half of the crepe.
Fold the other half of the crepe over the filling, then fold it again to form a triangle or square. Cook for 1-2 minutes per side, or until the cheese is melted and bubbly.
Repeat with the remaining crepes, ham, and cheese. Serve immediately.
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