- Mix the egg whites and milk together in a large bowl until well combined. 
- Spread honey mustard evenly on 4 slices of bread. 
- Layer Swiss cheese and ham on the mustard-covered bread, then top with remaining bread slices to form 4 sandwiches. 
- Dip each sandwich in the egg mixture, coating both sides thoroughly. 
- Spray a large nonstick skillet with cooking spray and heat to medium-high. 
- Place sandwiches in the skillet and cook until golden brown, approximately 3-4 minutes per side. 
- Flip sandwiches carefully and cook the other side until golden brown. 
- Remove from heat, sprinkle with powdered sugar, and serve immediately with raspberry jam on the side.