Roasted Red Onion and White Cheddar Tart

Ever since I’ve been a food writer (for several decades now), I’ve kept a file of recipes that serve as inspiration for my own creations. The folder is filled with newspaper and magazine clippings, and with hand-written or copied recipes friends have shared.

Several weeks ago I spotted a recipe in this cache for a gratin of red onions. Cooked slowly in the oven with garlic, thyme, and white wine, they were then covered with crème fraîche and cheese. The concept of this dish became the starting point for the roasted red onion tart featured here.

I roasted mild red onions until tender, sweet, and slightly crisp, piled them in a buttery pre-baked dough, and topped the mixture with some crème fraîche whisked with an egg yolk. Then I added a sprinkling of grated white cheddar. For the delicious crust, I used the exceptionally short and rich dough formula my friend, Barbara Morse, a professional baker, shared with me.

This rustic tart with its golden crust and dense filling could easily anchor a supper or lunch paired with a bowl of soup or a salad (try it for a March Madness meal!). Although the tart is best when baked and served soon after, last week, pressed for time, I made it a day ahead and reheated it with no problems.

Crust
1 1/2 cups all-purpose flour
3/8 teaspoon salt
3/4 cup (1 1/2 sticks) cold, unsalted butter, diced
1/4 cup ice water plus 1 to 3 teaspoons extra if needed

Filling
4 medium red onions (about 1 3/4 pound total)
3 tablespoons olive oil
1 1/2 teaspoons dried thyme
Kosher salt
Several grinds black pepper
1/2 cup crème fraitche
1 large egg yolk
Pinch cayenne pepper
1/2 cup (1 3/4 ounces) grated white cheddar

1. For dough, place flour, salt and butter in the bowl of a food processor fitted with the metal blade. Pulse until butter forms pea-sized chunks. Add water, a few tablespoons at a time and pulse quickly, just until dough forms a mass on the blade, using an extra teaspoon or two if mixture seems dry. Form dough into a disk, cover with plastic wrap, and refrigerate for at least 1 hour.

2. Roll dough on a lightly floured surface to about 1/8-inch thickness and transfer to a 9-inch tart pan with a removable bottom. Trim overhanging dough to 1/2 inch. Fold overhanging dough in and press to form double-thick sides that rise slightly above edge of pan. Pierce
bottom of dough with a fork. Refrigerate shell for 30 minutes. Tart shell can be prepared 1 day ahead; cover tightly with plastic wrap,
and refrigerate.)

3. Position a rack at center position and preheat oven to 375 degrees F. Line the tart shell with foil and fill with dried beans.

4. Bake the crust for 10 minutes, then remove the foil and beans, and bake 15 minutes more until crust is golden. If the crust starts to rise while baking, prick it with the tines of a fork. When done remove the tart shell from the oven and keep at room temperature.

5. For filling, peel onions and halve lengthwise through the root ends. Cut into 1/2 inch wedges keeping a little of the root end when possible so that wedges remain intact. Place the wedges on a large rimmed baking sheet, drizzle with olive oil, and sprinkle with thyme, 1/2 teaspoon salt, and pepper. Toss gently and then spread wedges evenly in a single layer.

6. Roast onions, stirring and turning every 10 minutes, until golden brown and tender, and some are slightly crisp around the edges, about
45 minutes. Remove and cool 5 minutes.

7. Arrange onions in the tart shell. In a small bowl, whisk together crème fraîche, egg yolk, 1/4 teaspoon kosher salt, and pinch of cayenne, and spread the mixture over the onions. Bake tart 20 minutes, sprinkle with cheese, and bake until cheese has melted, about 10 minutes more. Remove and cool 5 minutes. If you’d like, drizzle a few drops of balsamic vinegar over the tart to add a slightly tart accent.

8.To serve cut into 6 to 8 slices. Serve warm. Serves 6 to 8.

© Copyright Betty Rosbottom 2012

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