When cooking chard, you want to be able to enjoy both the leaves and stem, however, the problem can be that they cook at different rates. Instead of winding up with perfectly cooked leaves and undercooked stems, or well-cooked stems and over-cooked leaves, try separating them so they can both be cooked properly.
First, remove the leaves from the stem:Then, stack all the leaves on top of each other and roll them up:
Next, cut through the roll so that you wind up with thinly shredded pieces (this cut is called chiffonade):
Now, you can add just the stems to the pan and saute them first (I have some cut up scapes in there as well).
Once the stems are almost done cooking, add the leaves and mix them in. This way, both parts will be cooked just the right amount of time, and you can enjoy them together in one dish.