1. Combine Gouda cheese, cream cheese, honey and cinnamon in small bowl; stir until well blended. Spread cheese mixture evenly on all bread slices. Layer apple slices evenly over cheese on 2 bread slices; top with remaining bread slices.
2. Combine milk and egg in shallow bowl; stir until well blended. Dip sandwiches in egg mixture, turning to coat well.
3. Melt butter in large nonstick skillet over medium heat. Add sandwiches; cook 4 to 5 minutes per side or until cheese melts and sandwiches are golden brown. Sprinkle with powdered sugar.