Lay out the bread and spread a thin layer of Dijon mustard on one side of half the slices. If you like a creamier sandwich, spread mayonnaise on the other slices.

Layer each mustard slice with 1–2 slices of Swiss, then add ham and turkey. Top with another slice of Swiss to help everything melt together. Close with the remaining bread.

In a shallow bowl, whisk together eggs, milk or cream, a pinch of salt, and a little pepper until smooth.

Preheat a large skillet over medium heat. Add 1 tablespoon butter and a splash of oil to coat the pan.

Dip each sandwich into the egg mixture, turning to coat both sides. Let excess drip off so the bread doesn’t get soggy.

Place the dipped sandwiches in the hot skillet. Cook for 3–4 minutes per side, pressing gently with a spatula, until the bread is golden and the cheese is melted. Add more butter as needed for later batches.

Transfer cooked sandwiches to a wire rack or warm oven (200°F/95°C) while you finish the rest. This keeps the crust crisp.

Dust lightly with powdered sugar if you like, slice diagonally, and serve with raspberry or strawberry jam on the side for dipping.