For the kiev, heat a deep, heavy-bottomed pan, one-third filled with vegetable oil, until a breadcrumb will sizzle gently in it. (CAUTION: hot oil can be dangerous! Do not leave unattended.)
In a bowl, mix the butter with the chilli, garlic, parsley, and lemon juice.
Use a sharp knife to split the breast almost in half horizontally.
Open the breast out and place between two sheets of greaseproof paper. Bash the chicken with a meat mallet (or a rolling pin) to flatten the meat.
Place the butter mixture in the middle of the chicken. Fold over the meat so the butter is completely wrapped.
Dredge the chicken kiev in the seasoned flour, then dip into the beaten egg and then roll the kiev carefully in breadcrumbs. Repeat the egg and breadcrumbs process.
Carefully add the kiev to the hot oil and deep-fry for ten minutes. Remove from the oil and drain on kitchen towels.
Meanwhile, for the herby mash, boil the potato until tender, drain and return to the warm pan.
Add the butter, cream, chives and cheese to the pan and mash together well. Season, to taste, with salt and freshly ground black pepper.
To serve, place the kiev on a warmed plate. Slice open to release the melted butter and place a spoonful of herb mash beside.