Combine the butter, garlic, salt, Italian seasoning and black pepper into a bowl and stir well.
Brush eggplant with butter mixture and place on a grill. Cook over medium heat for about 4 minutes on each side or until tender. Set aside.
Balsamic Sun-Dried Tomatoes:
Heat one tablespoon olive oil in a skillet over medium heat and cook garlic until fragrant. Add sun dried tomatoes, then cook for about 50 seconds. Add balsamic vinegar and white wine and keep cooking until the juice evaporates for about 1-2 minute. Turn off the heat and set aside.
To Assemble Panini:
Slightly butter each side of sandwich loaf. Pre heat the grill pan over medium heat.
Top each slice with provolone, spinach, grilled eggplant, balsamic sun-dried tomatoes and top with another slice of sandwich loaf, butter side up.
Place a heavy skillet over the panini and press down, cooking for about 2 minutes on each side. Serve immediately.