1. For the dough: Dissolve the yeast and sugar in 1/4 cup warm water (105 to 115 degrees); set it in a warm place.

2. If egg is cold, cover it with hot water for a few minutes to bring it to room temperature. Mix 1 cup of the flour and the salt in a bowl, make a well in the center, and break the egg into it. Add the crème fraîche (or light sour cream) and the yeast mixture (now foamy). Mix all with a wooden spoon for a smooth, soft dough. Add more flour as needed.

3. Dust dough with flour, gather it in a ball, and place in a clean bowl. Cover. Let rise in a warm place 45 minutes. If not ready to proceed, punch it down and let rise again.

4. Flatten dough, put it in the center of tart pan and press it out to the edge. Add just enough flour to keep dough from sticking. If dough shrinks, cover with a towel, let rest 20 minutes, then finish shaping it to 1/4 inch above pan rim. Add the filling or refrigerate until needed.

5. For the filling: Cut chard leaves from stems. (Reserve stems for another use.) Chop the leaves into 1-inch pieces, wash thoroughly, drain in a colander, and set aside.

6. Heat the oven to 375 degrees. In a wide skillet, heat the butter and oil over medium heat; add the onion and cook it until it is soft and translucent, about 6 minutes. Add the garlic, the chard leaves (by handfuls until they all fit), and the salt. Turn the leaves with tongs, cooking them until tender, 5 to 7 minutes. When the mixture cools, squeeze out excess moisture with paper towels.

7. To make the custard, beat the eggs, then stir in the half-and-half, infused saffron, lemon zest, grated cheese, a few scrapings of nutmeg, and the parsley. Stir in the chard and onion mixture. Season with salt and pepper to taste.

8. Toast pine nuts in a small dry pan on medium heat until golden, 2 minutes. Add filling to tart shell. Top with pine nuts. Bake until set and golden, about 40 minutes.

Per serving (based on 8): 261 calories, 9 grams protein, 21 grams carbohydrates, 2 grams sugar, 16 grams fat, 136 milligrams cholesterol, 536 milligrams sodium, 2 grams dietary fiber.