For the chestnut and cabbage sprout vegetables, clean the cabbage sprouts and pluck off any wilted leaves. Score the stem crosswise on the cut surface so that the temperature can penetrate evenly.
Cut the roses in half if they are very large – it is nicer to leave them whole. Cook in boiling salted water for about 5 to 10 minutes. Drain and rinse with ice-cold water to retain bright color.
To serve, toss in butter. Use a wide saucepan or deep frying pan for this. The vegetables should have as much contact with the bottom as possible.
Cream the butter in it. Sauté finely diced shallot, add cabbage sprouts and chestnuts and toss to combine.
Do not stir, as the delicate chestnuts can break easily. Season with salt, pepper and a touch of cayenne. Cover and simmer for 5 minutes.
Then toss well again and arrange the chestnut-cabbage sprout vegetables in a warmed bowl and serve.