Preheat the oven to 375 degrees F (190 degrees C). Cut a shallow pocket into each chicken breast using a sharp knife.

Stuff each chicken breast with chopped tomatoes, sliced mozzarella, and about 2 tablespoons pesto. Mix cantanzaro herbs and garlic salt in a small bowl and sprinkle each chicken breast evenly with herb mixture.

Bake in the preheated oven until chicken is no longer pink in the center and the juices run clear, about 40 minutes. An instant-read thermometer inserted into the center should read at least 165 degrees F (74 degrees C).