1Blanch the chard leaves in a large pot of water. Drain, then squeeze the chard with your hands to get rid of any excess cooking water. Finely chop the leaves. Set aside.
2Chop the ham. Combine the ham with the chard and parmesan in a bowl. Add the eggs, one at a time. Taste and season with salt and pepper. The mixture should be quite loose. If this is not the case you can add an egg (it will depend on the size of your chard leaves) You need to be able to form balls easily that will not break apart.
3Sprinkle a platter generously with flour. Do the same on a plate. With a teaspoon, take a little filling and then make a flattened ball (like a gnocchi) with your fingers. Roll each ball in the flour plate and then put them on the platter. It is important to make them equal so they cook evenly.
4When the dumplings are ready, heat a large pot of salted water. Place the dumplings delicately into the water. When they are cooked they will rise to the surface.
5Remove them from the pot with a skimmer. Arrange on a platter and serve immediately with tomato sauce.