Season the chicken breasts generously with salt and pepper, then cook them using your preferred method: grill over medium-high heat for 6-7 minutes per side, bake at 375°F (190°C) for 25-30 minutes, or sauté until golden and cooked through. Ensure the internal temperature reaches 165°F (74°C). Let the chicken rest for a few minutes before slicing it thinly.

Take your chosen bread and spread a luscious layer of basil pesto on one side of each slice. On one slice, layer the tender, sliced chicken, followed by a generous helping of fresh mozzarella. Add sun-dried tomatoes if desired, then top with the second slice of bread, pesto side down.

In a skillet, heat a drizzle of olive oil over medium heat until shimmering. Place the assembled sandwich in the skillet and grill for 3-4 minutes per side, pressing down gently with a spatula. A panini press can also be used.

Once both sides are golden and the mozzarella is melted, remove the sandwich from the skillet. Allow it to cool for a minute, slice diagonally for presentation, and garnish with fresh basil.