Preheat oven to 200?C/400F/gas mark 6. Cut a deep pocket in the chicken breasts. Melt the butter, add baby spinach and allow to wilt for a few minutes. Add the roughly chopped Stilton, stir to incorporate into the spinach and butter mixture. Cool and place in the pockets of chicken. Wrap a slice of Parma ham around each breast and place in ovenproof dish. Season, adding moilly prat. Cook for 25 minutes. For the vegetables: Melt the butter in a large saucepan and add the shallots and garlic. Cook for 5 minutes, then add the vegetables, sugar and 50ml of water. Bring to the boil, cover and cook for about 5 minutes or until vegetables are tender and the liquid becomes syrupy. Toss the hot vegetables with chopped mint, mustard and vinegar and season well. Serve immediately, garnished with the mint sprigs.