To make the clarified butter - put the butter in a small clear glass bowl, then microwave in 10 second intervals until completely melted. Let it settle and you will see a milky residue on the bottom and the rest will be clear yellow. Carefully pour the clear fat into another small bowl or jug, leaving the milky residue at the bottom. Discard the milky residue.
Place the chicken breasts on a chopping board. Butterfly them by slicing through the middle and opening them up like a book. Cover with cling film and use a meat tenderizer or rolling pin to flatten them. Season with salt and freshly ground black pepper, then place a slice of ham and cheese inside each butterflied chicken breast and fold over. Crack the egg into a shallow bowl and whisk well. Put the plain flour in another shallow bowl and the breadcrumbs in another. Dip each chicken breast first in flour, then in egg, and finally in breadcrumbs. Put the breaded chicken breasts onto a plate, and place in the fridge until you’re ready to cook them (see Notes).
Preheat the oven to 180C fan/gas mark 4. About 3 minutes before you are ready to cook the chicken, heat the clarified butter in a large oven proof frying pan over a medium heat. Fry the chicken for 1 to 2 minutes on each side, basting the butter over the top and sides of each breast, until golden brown. Transfer to the oven and bake for about 15 to 20 minutes, or until the chicken is cooked through (74C). If you don't have an ovenproof frying, transfer the chicken to a sauté pan, or baking tray to bake them in the oven.
Remove from the oven and drain briefly on kitchen roll on a plate. We enjoy with some vegetables and potato salad on the side.