Quiche Lorraine With a Buckwheat Crust

Directions

1. Make the crust: Combine the flours, salt, and baking powder in the bowl of a stand mixer fitted with a paddle attachment. Mix on low just to combine. Use your fingers to break the cream cheese into pieces and add to the bowl. Mix on low until the cream cheese is mostly broken down and barely visible. Add the butter and mix on low until none of the pieces are bigger than a chickpea; this should take 30 seconds to 1 minute (if there are any stragglers, just stop the machine and smush the piece with your fingertips—don’t overmix). Combine 1 ½ tablespoons water and the vinegar in a small glass and, with the machine running, pour it in. Add additional water in ½-teaspoon increments if the dough looks dry. As soon as the sides of the bowl are no longer dusty and clumps and curds begin to form (it should not form a cohesive ball—that’s too far), turn the mixer off; better to undermix versus overmix at this point. Remove the bowl and bring the dough into a ball with your hands. Wrap well in plastic wrap and form into a flat disk. Refrigerate for at least 1 hour or up to a couple days. (You can also freeze the dough for future quiches; just thaw in the fridge overnight.)
2. Roll out and crimp the crust: On a floured work surface, roll out the dough into a roughly 12-inch circle, then transfer to a 9-inch pie pan (not deep-dish), making sure the bottom corners are tightly pressed against the pan. Use scissors to trim the dough to an even 1-inch overhang. Fold the edge under itself. Use your fingers to press and even out the sides. Crimp the edges however you’d like. (I like using my left hand’s thumb and pointer finger as a guide, then crimping with my right hand’s pointer finger, to form ruffles.) Stick in the freezer for at least 15 minutes or up to 2 days.
3. Parbake the crust: Heat the oven to 400°F. Line the frozen crust with a square of parchment, fill with dried beans (or another pie weight), then set on a sheet pan. Bake on the lower rack for about 40 minutes, rotating halfway through, until the crust is starting to brown along the edges and the bottom no longer looks raw and doughy. While the crust is baking, use a fork to whisk the egg white with a pinch of salt until it’s very loose. When the crust is done, remove the parchment and beans and prick the bottom of the crust a few times with a fork. Brush the inside of the crust with the salted egg white, then return to the oven to bake for another minute to set.
4. While the crust is baking, cook the bacon and shallots: Add the bacon to a cast-iron skillet and set over medium heat. Cook for about 8 minutes, until crisp. Use a slotted spoon to transfer the bacon to a plate. Pour most of the fat into a jar for another use (say, sautéing greens or pan-frying toast), leaving about 1 tablespoon in the pan. Add the shallots to the pan and cook over medium heat for 3 to 5 minutes, until softened and almost translucent. Use a slotted spoon to transfer the shallots to a plate to cool.
5. When the parbaked crust is out of the oven, lower the temperature to 325°F and turn your attention to the custard.
6. Make the custard: Combine the cream and milk in a bowl. Add the flour to another, smaller bowl and add a splash (about 1 tablespoon) of the liquid. Stir with a fork or whisk until smooth. Repeat this (splash, stir, splash, stir) until the flour mixture is completely smooth and pourable. Pour into the bigger bowl of cream and milk and stir. Add the eggs, egg yolk, salt, and pepper and whisk until smooth.
7. Fill the quiche: Sprinkle half of the cheese evenly over the bottom of the crust. Sprinkle the bacon and shallots on top, spreading them out as much as possible (even scooching up the sides is fine), so that you can see the cheese and crust below. There should not be a packed-solid layer of mix-ins; the custard filling needs to be able to get through. Sprinkle the remaining cheese on top. Slowly and evenly pour in the custard, taking it as high to the brim as possible. It should be on the verge of overflowing. (You likely won’t have any leftover custard, but if you do, microwave it in a ramekin as a snack.)
8. Bake the quiche, still set on the sheet pan, for 55 to 65 minutes, until it no longer shimmies when shaken. (If the crust starts to brown too much mid-bake, you can carefully tent it with foil.) Let cool until barely warm before slicing and serving. It’s also great at room temperature and cold.