Separate the stems from the chard leaves. Finely chop the stems and set
them aside. Slice the leaves thinly and set them aside. In a large pot over
medium heat, melt the butter. Add the onion and cook, stirring occasionally,
for about 5 minutes. Add the Swiss chard stems, garlic, thyme, and bay leaf.
Cook for about 1 minute longer. Pour in the wine and bring the mixture to
a boil. Reduce the heat to medium-high
and cook until most of the liquid
evaporates. Add the zucchini, stock, and a hefty pinch of salt and pepper.
Bring the liquid to a boil again. Reduce the heat to medium-low
and cook
until the zucchini is tender, about 8 minutes.