Cook the pasta, preferably firm to the bite. Rinse the chard thoroughly with cold water and cut into individual leaves. Cut the leaves into small pieces.
Finely dice onions and garlic and sauté in melted butter until translucent. Then add the chard and pour in the vegetable stock. Let simmer for approx. 5-10 minutes at a low temperature. Now puree everything into a sauce and stir in the creme fraiche. Don`t let it boil anymore! Season with salt and pepper to taste.
Finely dice the tomatoes and feta and either add to the sauce at the same time or sprinkle on the plate prepared with pasta and sauce.