Preheat the oven to 180 C / Gas 4. On a chopping board cut a deep pocket lengthways along the chicken breasts and slightly open out. Place the ham slice and cheese slice inside. Fold back down and secure with toothpicks.
Add some breadcrumbs to a bowl along with salt and pepper and the herbs. Carefully dip the chicken first into some flour, shake off the excess. Dunk in the beaten egg, drain off the excess. Now press into the breadcrumb mix. Repeat with the other chicken breast. I then repeat the whole process for a crunchier crumb. Place in the fridge for 10 minutes to firm up or make ahead in the morning until ready to cook.
Heat a nonstick frying pan with some butter and oil over a medium temperature. Add the chicken and brown off all sides, about 5 minutes. Be careful not to burn the breadcrumbs. Place into an ovenproof dish or pan.
Bake in the oven for about 30 minutes or until the chicken is cooked through. Some of the cheese may leak out so it is essential to secure the opening well.