Lay out the chicken thighs and sprinkle both sides generously with salt and pepper.

Heat grill to medium. When the grill is up to temperature, lay out the chicken thighs. Grill the thighs, turning a couple of times, for 10-12 minutes, or until the internal temperature of the thickest part reaches 165°F. Just before removing the chicken from the grill, lay out one slice of mozzarella over each chicken thigh. While that begins to melt, drizzle olive oil over the cut sides of the ciabatta rolls and lay them directly on the grill. When the cheese is hot all the way through, use a spatula to transfer the thighs and toasted rolls to a platter.

Spread 1 tablespoon of the Sun-Dried Tomato spread on the bottom, half of each roll, then 1 tablespoon of the pesto on the top half of each roll. Use a spatula to transfer one chicken thigh, melted cheese side up onto each roll's bottom half. Position the top half, pesto side down, on the chicken. If desired, slice the sandwich in half on the diagonal. Serve hot, warm, or room temperature.