The chef and gardener Deborah Madison has been writing almost entirely about vegetables for more than 25 years. This recipe comes from her book“Vegetable Literacy,” which breaks down the universe of vegetables into botanical families — the Carrots (carrot, celery, fennel, parsnips), the Sunflowers (sunchoke, cardoon, artichoke, endive, escarole, lettuce) and so on.
03While onions cook, whisk eggs with crème fraîche and milk. Stir in cooled onions, cheese and bacon, if using.
04To make the crust, put flour and 1/4 teaspoon salt in the bowl of a stand mixer fitted with a paddle attachment. Add 6 tablespoons butter and turn mixer to low speed until butter has broken into small, pebble-size pieces. Drizzle in ice water until dough looks clumpy and damp. (You’ll use about 3 tablespoons, fewer if butter was soft.) Form dough into a disk or a rectangle to correspond to the shape pan you’re using. You have a few choices: a 9-inch tart pan, a square tart pan or a rectangular one (11 by 81/2 inches), all with removable bottoms. Wrap dough in plastic and refrigerate.
05Heat oven to 400 degrees. Roll dough to fit tart pan, then drape dough in pan. Neatly press dough into pan and shape it. Set it on a sheet pan. Pour onion mixture into tart pan, and bake until surface is golden and browned in places, 45 to 50 minutes. Let cool to warm before cutting into slices and serving.