Lay out 4 slices of bread. On each slice place 2 slices of Swiss cheese, 2 slices of ham, and 2 slices of turkey (stack cheese below meat so it melts into bread). If using cheddar, place one slice on top of the meat. Top each with remaining slice of bread to form 4 sandwiches. Lightly spread 1/2 tablespoon of softened butter on the outside of each sandwich (both top and bottom).

Press and chill (optional)

If time allows, press sandwiches lightly with a spatula and refrigerate 10 minutes to help them hold together for dipping and frying.

Batter & Cook

Make batter

In a shallow wide bowl or pie plate, whisk together eggs, milk, flour, salt, black pepper, and dry mustard until smooth and slightly frothy. Batter should be slightly thicker than milk but still pourable; adjust with 1 teaspoon milk if necessary.

Dip sandwiches

Heat a large nonstick skillet or griddle over medium heat. Add 1 tablespoon butter and let it melt. Holding each sandwich closed, dip front and back into the egg batter, allowing excess to drip off — do not soak so long that bread falls apart. Repeat for each sandwich and place onto the hot skillet.

Fry until golden

Cook sandwiches 3–4 minutes per side, pressing gently with a spatula, until batter is set and crust is deep golden brown and cheese is melted. Add additional 1 tablespoon butter to pan as needed between batches to prevent sticking and encourage browning.

Finish in oven (optional)

If sandwiches brown before cheese melts, transfer finished sandwiches to a 350°F (175°C) oven on a baking sheet for 5 minutes to finish melting through.

Finishing & Serving

Slice and dust

Transfer sandwiches to a cutting board and let rest 1–2 minutes. Slice each sandwich diagonally into halves or quarters. Lightly dust the tops with powdered sugar (about 1/2 tablespoon per sandwich) for the classic sweet-savory contrast.

Serve

Serve warm with small bowls of jam and optional maple syrup for dipping on the side. Recommend one sandwich per person; adjust to taste. Leftovers can be reheated in a skillet for best texture.