1 Separate the green and white parts of the chard. Peel the white part, then slice it.
2 Blanch the green part of the chard in boiling water for about 2 minutes, and 5 minutes for the white part. Strain.
3 Heat the saucepan with butter to 2/3 of the maximum power of your heat source. When the butter foams, add the white part of the chard and cook covered for 15 min over low heat.
4 At the end of cooking, add the previously sliced green part of the chard.
5 Cook the spaghetti separately in boiling salted water and then add to the chard.
6 Season and serve with grated Parmesan and truffle slices.