Heat a large skillet over medium high heat. Butter all 4 slices of Italian bread.

Place two slices of the bread in the plan. Place 1 slice of Gouda cheese on top of each followed by 4 slices of apple and then another slice of Gouda cheese.

Quickly spread the remaining 2 slices of bread with brown mustard on the side opposite the butter. Place the bread mustard side down on top of the sandwiches in the pan.

Cook for 3-4 minutes per side or until the cheese is melted and the bread is brown and crisp.

Remove from the pan, cut sandwiches in half and enjoy!