To make breadcrumbs from scratch, tear a loaf of bread (day old is fine) into large chunks, and don’t remove the crusts. Use a food processor to process until they are the processed to your liking. I prefer them still quite chunky (around 3mm for the larger pieces) as it makes for good, crunchiness once cooked. Now transfer them to a large cookie tray and spread them out evenly. Toast in a 150C / 300F, mixing occasionally until they are quite dry. Done. These can be frozen until required.
Lay the chicken breasts between two sheets of plastic wrap. Use a meat mallet to pound the breasts until they are even thickness (about 1 – 1.5 cm thick).
Transfer the chicken to a chopping board. Season both sides well with salt and pepper. Depending on size, lay 4-5 sage leaves over the top of each chicken breast. Sprinkle half of the parmesan over each one then lay 2 pieces of prosciutto over each. Cut each chicken breast in half, through the middle.
Mix together the breadcrumbs, paprika, oregano and sea salt flakes and pour into a wide dish. Pour the beaten egg into another dish and the flour into a third dish. Carefully take one piece of chicken place it in the flour. Use 2 hands so you don’t lose any toppings. Turn it over to coat the other side and make sure there is no bare bits of chicken poking through. Repeat this process with the egg and finally the breadcrumb mix, then lay the chicken on a plate. Repeat with the last 3 pieces and transfer to the fridge for ½ an hour. This will help everything adhere nicely making it easier come frying time.
Pour the oil into a large, heavy based saucepan (it should be no more than 1.5cm deep) over high heat. Line a baking tray with kitchen paper towel, then sit a cooling rack over the top. Heat the oil to 180C / 350F on a thermometer or if you don’t have one, keep testing with breadcrumbs until one thrown in sizzles straight away. Gently place 2 pieces into the oil and fry for 8 minutes, turning halfway through. Transfer to the cooling rack and test for doneness. Allow to drain well before serving.