From The Greens Cook Book by Deborah Madison and Edward Espe Brown
1 recipe Yeasted Tart Dough.

1 large bunch of Chard, enough for 6 to 8 cups of leaves, roughly chopped
1 TB Butter
1 TB Olive Oil
1 large Onion (calls for a yellow onion) cut into 1/4 inch square
2 cloves Garlic, finely chopped
3/4 tsp Salt
3 Eggs
1.5 cups Milk or Cream
Large pinch Saffron Threads, soaked in 1 TB hot water
1/2 tsp Lemon Peel or 1/4 tsp Orange Peel, grated OR use 1 TB finely chopped Lemon Verbena Leaves
3 TB Parmesan
Nutmeg to taste
1 TB Parsley, chopped
Pepper
3 TB Pine Nuts

Prepare the yeasted tart dough and set it aside to rise in a warm place.  Cut the chard leaves away from the stems, and save the stems for another purpose.  Chop the leaves into pieces roughly an inch square, wash them in a large bowl of water and set them aside in a colander.  Heat the butter and oil in a wide skillet, add the onion, and cook it over medium heat until it is translucent and soft.  Add the garlic and then the chard leaves, by handfuls until they all fit, and the salt.  Turn the leaves over repeatedly with a pair of tongs so that they are all exposed to the heat of the pan, and cook until they are tender, about 5 minutes or more.  Prepare the tart shell; then make the custard.  Beat the eggs; then stir in the milk or cream, unfused saffron, lemon, or orange peel or lemon verbena leaves, grated Parmesan, a few scrapings of nutmeg, and the parsley.  Stir in the chard and onion mixture; taste and season with more salt, if needed, and freshly ground black pepper.  Preheat the oven to 375 F.  Toast the pine nuts in a small pan until they are lightly colored.  Pour the filling into the tart shell and scatter the pine nuts over the surface.  Bake until the top is golden and firm, about 40 minutes.