Brush one side of each slice of bread with a thin coating of Dijon Glaze. Spread mayonnaise on 1 slice per sandwich. Layer 1/4 of the onion and ham, a layer of apple slices, a slice of cheese on mayonnaise slice, and top with remaining slice of bread. Brush the top and bottom of each sandwich with oil and grill in a pan or sandwich grill (don't press the top of the grill) until the bread is crisp and golden brown and the cheese has melted.