Start by laying out your thick white bread on a clean surface. Layer 2 slices of deli ham and 2 slices of Swiss cheese between two slices of bread for each sandwich, pressing gently to secure them. Assemble a total of 4 sandwiches.

In a shallow bowl, whisk together 4 large eggs, 1 cup of milk, and optional Dijon mustard, seasoning with a pinch of salt and pepper.

Place a non-stick skillet over medium heat and add a generous tablespoon of butter, allowing it to melt completely.

Carefully dip each assembled sandwich into the egg batter, coating both sides thoroughly.

Place the dipped sandwiches in the hot skillet, cooking for 3-4 minutes on each side until golden-brown.

Once cooked, remove the sandwiches from the skillet, let them rest on a paper towel, dust with powdered sugar, and serve hot alongside jam.