Place potatoes in a pot, cover with water, bring to a boil and cook until tender in salted water, 15 minutes.
Preheat broiler to high.
Arrange the chops on a slotted broiler pan and season with salt and pepper on both sides. Finely chop garlic with a handful each of the parsley and mint, then reserve. Combine salad of fennel, coarsely chopped remaining mint and parsley leaves, radishes, scallions, celery, romaine, radichio and ricotta salata, in large bowl. Combine the lemon zest, lemon juice and marmalade. Whisk in the olive oil and pour dressing over salad. Toss and season with salt and pepper, to taste.
When potatoes are just about ready, broil lamb chops 2 minutes on each side for rare, up to 4 minutes on each side for well doneness.
Drain potatoes and transfer back to the hot pot to dry. Add peas, milk and soft cheese then mash to desired consistency. Add in reserved garlic and mint mixture and salt and pepper, to taste.
Serve chops alongside piles of salad and potatoes.