In a mortar, crush two of the garlic cloves to a puree with a large pinch of salt and the chopped rosemary. Add 2 tablespoons of the white wine and a dash of oil. Use this mixture to marinate the chops for at 1½ hours, or overnight.
Preheat the oven to its highest setting. Peel the beetroot and cut them into wedges. Toss in a large bowl with 2 tablespoons of oil, salt and pepper, then spread out evenly in a single layer in a baking tray. Drizzle a little extra oil over them and place in the oven to roast. You'll need to check them every 5-10 minutes and give them a shake or a stir so they don't burn - the goal is to get them soft, sweet and well caramelised.
Pour a thin layer of oil over the base of another baking tray and place it in the oven. Peel the potatoes and cut them into pieces the same size as the beetroot. Put them in a saucepan with cold water, bring to the boil and simmer for 1-2 minutes, until the outside is just starting to feel a little tender. Drain the potatoes in a colander, shaking them vigorously to roughen the outsides. Then leave them in the colander over the hot saucepan for a minute or two to steam.
Sprinkle the potatoes with salt. Remove the oiled baking tray from the oven and carefully add the potatoes, being sure not to splash yourself with the oil in the process. Place in the oven for 20 minutes or so, until the potatoes are crisp and golden brown, turning them once or twice whilst they're cooking.
Meanwhile, place a smallish, heavy-bottomed saucepan over a high heat. Heat some butter and lightly fry the remaining garlic, adding the capers when the garlic has started to take on a little colour. Fry until the garlic has browned a little more and the capers have crisped up a bit.
Stir in the flour, reduce the heat a little and cook for a couple of minutes, stirring frequently. Remove the pan from the heat and pour in the remaining white wine, stirring constantly to form a smooth paste. Return the pan to the heat and cook for a minute or so.
Add the stock to the sauce gradually, stirring to incorporate all the liquid before adding more. Add the thyme then turn down the heat and leave the sauce to simmer until ready to serve.
Preheat a griddle or grill. When the beetroot and potatoes are cooked they can be placed in a serving dish and kept warm in a low oven.
Lift the mutton chops from their marinade. Sprinkle salt and pepper on both sides of the chops and place on the griddle or under the grill. Cook for 5-6 minutes on each side -they will be nicest medium rare, so take them off the heat when they still have some give to a gingerly prodding finger. Leave to rest them in a warm place for 4 or 5 minutes.
. To finish the sauce, add the cream, parsley and season to taste with salt and pepper. The sauce should be the thickness of lightly whisked cream, coating the inside of your mouth, but not cloyingly.
. To serve, place two chops per person on serving plates with some piping hot vegetables and a good helping of the sauce.