In a bowl, sift together flour, sugar, baking powder, and salt.

In another bowl, whisk together the milk and egg until well blended.

Combine the wet and dry ingredients, mixing until smooth and free of lumps. The batter should be runny but thick enough to coat the sandwiches. Add a bit more milk if needed.

Assemble the sandwiches by layering a slice of Swiss cheese, followed by four slices of meat, and another slice of Swiss cheese. Top with another slice of bread. Keep the sandwiches whole for frying to maintain the cheesy goodness. Slice them after cooking.

Secure each sandwich with toothpicks at the corners.

Dip each sandwich into the batter, ensuring it's fully coated. Fry in oil heated to 340°F until golden. For regular bread, increase the oil temperature to 360°F.

Drain the sandwiches on paper towels after frying.

Remove toothpicks and sprinkle with powdered sugar if desired. For a classic touch, serve with raspberry jam for dipping.