1 recipe Tart Dough (recipe follows)
1 large bunch of chard, leaves only, roughly chopped
1 tablespoon butter
1 large yellow onion, chopped
2 cloves garlic, minced
kosher salt and freshly ground black pepper
1 1/2 cups whole milk
large pinch saffron threads, soaked in 1 tablespoon hot water
zest of 1 small lemon
3 tablespoons freshly grated Parmesan
3 tablespoons pine nuts, toasted
3 cups all-purpose flour
2 tablespoons sugar
1 3/4 teaspoons salt
1 cup plus 2 tablespoons (2 1/4 sticks) chilled unsalted butter, cut into 1/2-inch cubes
8 tablespoons (or more) ice water
1 1/2 teaspoons apple cider vinegar
Preheat the oven to 375ºF. Roll out one disk of dough to a 14-inch circle. Carefully transfer the dough to a 10-inch fluted tart pan. Fold the edges over on themselves to create a thick crust. Pierce the bottom of the dough with a fork in several places, then place in the freezer for 15 minutes.
Line the pan with foil and fill with pie weights or beans. Bake in the oven until the edges of the crust are starting to brown and the bottom no longer looks doughy, about 25 minutes. Remove from the oven and set aside to cool.
Heat the butter in a wide skillet; add the onion and cook it over medium heat until it is translucent and soft. Add the garlic, and the chard leaves by handfuls, if necessary, until they all fit. Sprinkle in a large pinch of 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, 5 minutes or more.
Make the custard. Beat the eggs; then stir in the milk, infused saffron, lemon peel, grated Parmesan, and a few scrapings of nutmeg. Stir in the chard and onion mixture. Taste and season with salt and a few grinds of pepper. Pour the filling into the prepared tart shell and bake until the top is golden and firm, about 40 minutes. Scatter the pine nuts over top before serving.
Note: You will need only 1 disk of this dough for the tart so keep the other one in your freezer for next time!
Blend flour, sugar, and salt in a food processor. Add butter; using on/off turns, process until coarse meal forms. Add 8 tablespoons ice water and cider vinegar; blend until moist clumps form, adding more ice water by the teaspoon if dough is dry.
Gather dough together. Turn out onto work surface; divide dough in half. Form each half into ball and flatten into disk. Wrap disks separately in plastic and refrigerate 1 hour. (Can be made ahead. Keep dough refrigerated up to 2 days, or enclose in a resealable plastic bag and freeze up to 1 month. Thaw in the refrigerator overnight.) Soften slightly at room temperature before rolling out.