Let's cook.
Spread 1/2 teaspoon of butter on one side of each sourdough bread slice.
Flip two slices of bread over so the unbuttered side is facing up. Spread 1/2 teaspoon of Dijon mustard on the unbuttered side of these two slices.
Layer half of the turkey, half of the apple slices, and half of the cheddar cheese on top of the mustard-coated bread slices.
Place the remaining two bread slices (buttered side up) on top of the cheese, forming two sandwiches.
Heat a large skillet or griddle over medium heat. Once hot, place the sandwiches buttered-side down in the skillet.
Cook for 3-4 minutes per side, or until the bread is golden brown and the cheese is melted and bubbly. Press gently with a spatula to ensure even browning.
Remove from skillet, slice in half, and serve immediately.
Save this recipe so you can find it again.