Remember quiche? Sure, you remember the long-ago craze, the mockery, even the New Yorker cartoons. But do you remember the thing itself? Although it's still served in plenty of restaurants - and although a good quiche makes a terrific meal - it doesn't figure on my gastro-map as prominently as it used to. But this past weekend, Jackie and I served a side dish that, in a roundabout way, called it to mind: Pureed celery root (celeriac) and potatoes. As always when making this, I'd simmered the celery root in milk and a little cream, some of which went into the puree along with the usual butter and seasonings. As it cooks, the milk takes on a gentle but evident flavor and aroma of celery; I always save it for a while but it tends to get lost in the fridge and is eventually thrown away.
Not this time: It occurred to me that used as the basis for the filling of a quiche it would contribute that additional flavor to the custard. So quiche is what we had for supper the next night. Apart from the celery-infused milk, my choice of ingredients was not novel: bacon, leeks and Gruyère cheese. Nor was there anything unusual in the way I made it, though I do have a couple of tips that might help achieve success.
The first tip relates to the pastry: To ensure a completely cooked, crisp shell, bake it through, not just partially, before adding the filling. Even though it will be cooked further with the garnish and custard, it will not over-bake, because the filling will insulate it from the oven's heat. The dough itself was an ordinary pâte brisée or butter-based pie dough: for a 22-cm (circa 8-1/2-inch) fluted tart tin with a removable bottom, I rubbed together a generous 4 ounces (say, 120 g - or, if you insist on not weighing your ingredients, something less than one cup) of flour, 2-1/2 oz (70 g or 5 tablespoons) butter and enough salt that I could really taste it, then moistened it with sufficient cold water to bring it together. When it had rested and firmed up in the refrigerator (enclosed in plastic wrap), I rolled it out and lined the tart tin, which I then lined with aluminum foil and placed in the freezer; I am convinced that freezing prevents the dough from sliding down the sides of the tin.
Meanwhile, I cut 2 oz. (60 g) sliced smoked bacon crosswise into 1/4-inch (6 mm) rectangles and cooked them slowly until they were somewhat crisp, but not carbonized, and much of the fat had rendered out. I halved the white and pale green part of a medium leek lengthwise, then cut it across into thin half-moons (which came apart into half-rings). I rinsed the leek in cold water, drained it well, and cooked it in butter over medium-low heat with salt and pepper until tender - this took only a few minutes. I left these two things to cool, and shredded 2 oz. Swiss Gruyère on the coarse side of a box grater.
Once the pastry shell was frozen, I placed baking weights (dried beans in our house) into the foil-lined shell and baked it (on a sheet pan) in a 400 degree F (205 or so C) oven for 20 minutes, removed the foil and beans and returned the pastry to the oven for another half hour; start checking it for golden-brownness 20 minutes in, especially if you have a convection oven.
I warmed but did not boil 1-1/3 cups (305 ml) of the celeriac-scented milk, then, in a bowl, whisked it gradually and gently into three egg yolks and one whole egg. It was already well salted, so, after tasting, I seasoned it with pepper and a little nutmeg. (That is the second tip: With the shell pre-baked you can fill it with still-warm custard, which will set a little more quickly and evenly than a cold mixture.)
When the shell was baked, I distributed the leeks and bacon across the bottom, then the cheese. I poured in the custard mixture - still warm but by no means hot. It didn't all fit into the shell, but it might fit into yours. This went back into the oven for another 35 minutes (start checking after 20), when it was nicely, spottily browned on top. I got it onto a cooling rack and let it settle for a quarter of an hour before serving.
The bacon masked some (not all) of the celeriac flavor in the custard, but that flavor was definitely present and made a real contribution. If I could live without bacon in a quiche, I'd omit it next time, but let's be realistic: To quote one of my Twitter pals, "one always wants the bacon." And the quiche was delicious, with an almost meaty taste from the farmers' market leek, which had been carefully stored by the grower since summertime. We ate one slice each, then another, then just a tiny acute-angle wedge more. Lucky we hadn't invited anyone over.
Ideally, I'd serve this with a salad simply dressed with olive oil, salt and a few drops of lemon juice. But the only leafy green vegetable in the house was parsley - and not in sufficient quantity to constitute a salad. So I cut a carrot into fine julienne, tossed in some of that parsley and dressed it in the same way: oil, lemon, salt and pepper. Not the perfect accompaniment, but not half bad.