Preheat oven to 400°F.
Run a rolling pin over the slices of bread to make them thinner.
Season apples with nutmeg and salt then dress with lemon juice. Combine with cheese.
In a small bowl, combine Dijon mustard and maple syrup. Spread mixture on each slice of bread.
Place some of the apple-cheese mixture over each slice of bread on top of the mustard-syrup. Fold the corners of the bread together to create a triangle. Squeeze sides together to ensure they are well-sealed.
Arrange turnovers on a rack set on top of a baking sheet. Bake 10 minutes until golden brown.