Use a meat mallet or rolling pin to pound each chicken breast between two pieces of plastic wrap until evenly thin. Rub each piece of chicken with a tablespoon of olive oil and season with pepper and a bit of salt (the cheese and prosciutto are already salty).
Preheat the oven to 200˚C (392˚F).
Heat some oil in a frying pan and fry 12 sage leaves until golden and crispy. Remove them and let them drain on a piece of kitchen paper.
Increase the heat slightly and cook the chicken breasts for about 2 minutes on each side. Remove from the pan and set aside.
Finely chop about 4-5 sage leaves.
Add the butter to the pan. Once melted, add the garlic, chopped sage, and onion. Cook until the onion is somewhat translucent. Add the wine and let it simmer until reduced by about half. Then add the broth, lemon juice, and chili flakes. Stir everything together and turn off the heat.
Place a slice of prosciutto and then a slice of cheese (or two) on each piece of chicken.
Place in the oven for about 10 minutes until the chicken is fully cooked and the cheese is nicely melted.
Remove from the oven and serve with the fried sage leaves.
