Ukrainian
Mash the butter with the herbs, crushed garlic and a pinch of salt, shape it into a 12 cm log on baking paper and freeze for 20 minutes until firm.
Butterfly each chicken breast, cover it with plastic wrap and pound it to an even 5 mm thickness, then season with salt and pepper.
Cut the butter into 4 sticks, place one on each breast and roll the chicken tightly around it, tucking in the ends so the butter is fully enclosed.
Dredge each roll in flour, dip it in beaten egg and coat it in breadcrumbs, then repeat the egg and breadcrumb layer and chill for 15 minutes.
Heat the oil in a deep pot to 170C and fry the rolls two at a time for 4-5 minutes until golden.
Transfer them to a baking tray and bake at 180C for 12-15 minutes, until the chicken reaches 74C in the center.
Rest for 3 minutes before serving and cut carefully, as the butter inside is very hot.