Wash the chard and clean thoroughly. I always take 1 to 3 bushes of Swiss chard, it depends on how big they are. I prefer the young, small perennials, I take 2 to 3 of them.
Then separate the leaves from the stems (cut along the rib). Pick up a few stems, preferably from the young leaves. Cut the leaves into wide strips and finely dice the stems. Wash tomatoes, peel them if the skin is very firm, remove the seeds and cut the pulp into small cubes.
Heat a large pan and add half the butter. Add the diced stems and sauté until translucent. Then add the chard, put the rest of the butter on top and cover with a lid (or aluminum foil) and let cook for about 8-10 minutes.
Cook the pasta in a large saucepan with sparkling salted water until al dente.
Mix the cream with the mustard and whisk well. Season with a little salt and pepper.
When the chard has collapsed, add the mustard cream and simmer gently for about 3 - 5 minutes. Then add the tomato cubes and let cook again, covered, for about 5 minutes. Season to taste with salt, pepper and nutmeg.
Drain the pasta well and add to the sauce in the pan. Mix carefully, serve immediately with freshly grated Parmesan.
A nice leaf salad with balsamic dressing goes well with it