Cut a deep slit along one side of each chicken breast, without slicing right through, then open it out like a book.
On a clean chopping board finely chop 4 sage leaves and mix them into the ricotta and season with salt and pepper to taste.
Lay 2 ham slices on the board overlapping them slightly and put a sage leave in the middle. Lay an open chicken breast on the top and spoon a quoter of the ricotta mixture onto the middle of the chicken. Fold the sides together to enclose the filing and wrap the ham slices around the stuffed chicken breast and then all of it in a cling film. Repeat with the rest of the chicken breasts and transfer them into the fridge for 2 hours to firm up.
Heat the oven to 360ºF / 180ºC and place a baking tray in the oven to heat up.
Heat a frying pan and drizzle a bit of olive oil. When it heats up, fry the ham-wrapped chicken breasts until they get browned – about 2 min on each side. Transfer them onto the heated baking tray and lay a few thyme springs on each chicken breast. Cook in the oven until the meet feels firm when you press it – about 15 min.
Rest the chicken covered with foil in a warm place for 5 to 10 min. Slice each stuffed breast thickly and arrange on a warm plates.
