Chard, Cheese & Caramelized Onion Tart
Also called greens and caramelized onion quiche
A savory custard tart of caramelized onions, greens and sharp cheese. Works with chard, kale or spinach.
- Makes
- one 9-inch tart, 6 to 8 servings
Ingredients
Amounts are for the recipe. Sizes, times and temperatures in the method are not scaled.
Crust
Filling
Amounts worked out from the other system are rounded.
Method
Blind-bake the crust
Roll out the crust and fit it into a 9-inch tart pan (a removable bottom is best) or pie dish, pressing it into the corners and up the sides. Trim the edges flush with the rim and dock the bottom all over with a fork. Freeze 20 minutes, which keeps it from shrinking.
Heat the oven to 375°F. Line the chilled crust with parchment and fill it with dried beans, rice or sugar. Bake 25 minutes. Remove the parchment and weights and bake another 10 to 15 minutes, until the bottom is dry and light golden. If the crust puffs, press it down gently with a spatula. Cool in the pan.
Filling
Caramelize the onions. Melt the butter (28 g2 tbsp) in a large skillet over medium heat. Add the onions (2) and the kosher salt (½ tsp). Cook, stirring every few minutes, until deeply golden and sweet, 25 to 35 minutes. If they start to stick, add a splash of water and scrape the bottom. In the last minute, add the balsamic vinegar (10 g2 tsp) and stir until it is absorbed. Transfer to a bowl.
Cook the greens. In the same skillet, melt the butter (14 g1 tbsp) over medium-high heat. Add the chopped greens in batches; they wilt dramatically. Season with salt and pepper. Cook until tender and most of the moisture has evaporated: 3 to 5 minutes for spinach, 5 to 8 for chard, 8 to 10 for kale. Squeeze out the excess moisture with the back of a spoon or in a clean towel, since wet greens make a soggy tart. Let cool slightly.
Make the custard. Whisk the eggs (3), the milk (120 ml½ cup) and the nutmeg until smooth.
Assemble and bake
Heat the oven to 375°F. Spread the onions over the bottom of the crust, layer the greens over them, and scatter the cheese (170 g1½ cups) on top. Pour the custard over everything; it should come to just below the rim. If it looks too full, hold back a couple of tablespoons.
Bake on a middle rack for 35 to 40 minutes, until the custard is set. The center should jiggle slightly like Jell-O when you nudge the pan, not slosh. The top should be puffed and golden in spots, and a knife in the center should come out clean or with just a film of custard.
Cool 10 to 15 minutes before slicing; the custard firms as it cools. Serve warm or at room temperature.
Notes
- Crust. Good with a whole wheat crust. Sugar works well as a pie weight, and you can reuse it for baking.
- Cheese. Gruyère is classic and melts well. Sharp cheddar is more assertive. Aged gouda adds a caramel note that suits the balsamic onions. Comté is another good choice. Grate it coarsely for pockets of melted cheese; finely grated cheese disappears into the custard.
- Greens. Spinach is mildest and cooks fastest but holds the most water, so squeeze it hard. Chard is earthier and has the most color. Kale is the sturdiest; use lacinato, not curly, and cook it longer.
- Milk. ½ cup is enough to bind the filling in a standard 9-inch crust, and more overflows. In a deep tart pan you can go up to ¾ cup.
- Make ahead. The crust can be blind-baked a day ahead and kept wrapped at room temperature. The onions and greens can be cooked a day ahead and refrigerated. The finished tart keeps 3 days in the fridge and reheats well at 325°F for 15 minutes.
- Variations. Render 100 g lardons or diced pancetta in the pan before the onions. Stir a few tablespoons of thyme, chives or dill into the custard. Use sherry vinegar in place of the balsamic for a sharper, less sweet onion.