This is my original recipe, a riff on the classic French Tarte aux Blettes. It's worth the effort to find the chestnut flour for the crust as the nuttiness is delightful with the savory filling. This is a lush and luxurious way to present chard, and you can serve it proudly to anyone, even the French Ambassador! - Abra Bennett —Abra Bennett
Test Kitchen Notes
Making this tart requires a bit more effort than I typically can spare on a weeknight, but it certainly is worth it. The chestnut flour crust, full of fresh herbs, seemed a bit difficult to handle at first, but after minute or so, rolled out like a dream. When cooked, it’s fragrant, with the mildly sweet, almost earthy flavor of the chestnut flour apparent but not overwhelming. The filling itself is rather simple, but thoughtfully constructed, to allow the chard to hold center stage. Altogether this is a lovely, not-too-rustic, just-a-bit elegant tart worthy of Editors’ Pick honors. ;o) – AntoniaJames —The Editors
Place the flours, chopped herbs, and the butter, cut in chunks, in the food processor. Pulse 6-7 times until the butter remains in pea-sized chunks.
Turn the mixture out into a bowl and with a fork stir in the ice water. On a lightly floured board or marble slab, turn the dough over gently a few times just until it holds together.
Form the dough into a disk, wrap it in plastic wrap, and chill for an hour.
Rainbow Chard Filling
Preheat oven to 425°.
Dice the chard stems into a fine dice. Make a chiffonade with the chard leaves by stacking them up, rolling them lengthwise, then slicing across the rolled leaves until you have a pile of fine strips.
Slice the whole bunch of green onions, keeping the green and white parts separated.
Heat the olive oil in a large skillet. Add the diced chard stems and the white parts of the green onions and sweat them, covered, over a low flame, for 5 minutes.
Add the chard leaf chiffonade and the sliced onion greens to the pot. Salt, pepper, and sprinkle with the quatre épices. Cover the skillet and sweat the vegetables together for another 5 minutes. The chard should be tender to the bite and highly seasoned. Remove from the fire and let cool.
Roll out the dough and fit it into a removable bottom 10" tart pan.
Whisk together the crème fraîche, cream, eggs, and egg yolks. Stir in the cooled vegetables.
Pour mixture into the tart shell and set the tart in the hot oven for 15 minutes. After 15 minutes reduce the temperature to 350° and continue baking the tart for another 25-30 minutes, until the surface is golden, slightly puffed, and lightly firm.