How to Make It
Preheat the oven to 450°. On a lightly floured work surface, stack the 2 rounds of pie dough and roll together into a 16-inch round. Ease the round into a 9-inch springform pan, pressing into the bottom and up the side. Trim the dough, leaving 1/4 inch of overhang. Tuck the dough under itself and crimp the edge decoratively. Line the dough with parchment paper and fill with pie weights or dried beans. Bake for about 15 minutes, until lightly golden. Transfer to a rack to cool. Reduce the oven temperature to 375°. Remove the paper and weights.
Meanwhile, in a food processor, pulse the jalapeños and crushed garlic until finely chopped. Add the parsley, cilantro, cumin, coriander, cayenne and olive oil, season with salt and pepper and pulse the zhoug until blended.
In a large nonstick skillet, melt the butter. Add the onion, season with salt and pepper and cook over moderate heat, stirring occasionally, until softened, about 8 minutes. Add the minced garlic and cook for 2 minutes. Scrape the mixture into a large bowl and cool to room temperature.
Add the eggs and heavy cream to the onion and beat until combined, then mix in the spinach, feta, 3/4 teaspoon salt, 1/8 teaspoon pepper and 1/4 cup of the zhoug. (Refrigerate or freeze the remaining zhoug.) Pour the filling into the quiche shell and bake for about 1 hour and 10 minutes, until the center is set. Tent the crust with foil if the edge starts to get too dark. Transfer the quiche to a rack to cool for about 30 minutes before serving with extra zhoug, if desired.