Top-ranked recipe named "Croque-Monsieur"
1. Use 2 tablespoons of the butter to spread over on one side of each slice of bread. (Add mustard and mayonnaise now, if wanted) Add 3 slices of ham, and 2 slices of Swiss cheese for each sandwich (3 sandwiches).
2. In a flat bottomed dish, whisk together the flour, baking powder, salt, eggs, and water until blended. Set aside.
3. Heat remaining butter and vegetable oil in a large skillet over medium heat. Dip both sides of each sandwich in the egg mixture, and fry in the oil and butter until browned, flipping to brown on each side.