Preheat your oven to 375°F (190°C).
Mix panko breadcrumbs and Parmesan cheese together in a shallow dish.
Season both sides of the chicken breasts with salt and pepper.
Press each chicken breast into the breadcrumb mixture until well-coated.
Heat olive oil in a skillet over medium-high heat. Brown each side of the chicken for about 3 minutes until golden brown.
Transfer the browned chicken breasts to a baking sheet. Bake for 15–20 minutes until they reach an internal temperature of 165°F (74°C).
Butter one side of each slice of sourdough bread. Grill these slices butter-side down until crispy and golden brown.
Once baked, slice your chicken into thin strips.
In a mixing bowl, toss chopped romaine lettuce with Caesar dressing until evenly coated.
Layer dressed lettuce, sliced chicken, and optional cherry tomatoes between two slices of grilled sourdough bread.
Serve your Crunchy Chicken Caesar Sandwich immediately while warm.