Season the chicken breast evenly with sea salt, black pepper, and garlic powder.
Heat a grill pan or outdoor grill to medium-high heat and cook the chicken for 6-7 minutes per side until the internal temperature reaches 165°F.
Remove the chicken from the heat, let it rest for 3 minutes, then slice it into thin strips.
Spread the ghee on one side of each sourdough bread slice.
Place one slice of bread, ghee-side down, in a clean skillet over medium heat.
Layer the sliced chicken, fresh mozzarella, tomato slices, and basil leaves on the bread.
Drizzle the balsamic glaze over the basil, then top with the second slice of bread, ghee-side up.
Grill for 3-4 minutes per side, pressing down slightly with a spatula, until the bread is golden brown and the cheese has melted.