Ingredients
1 1/2 c. whole wheat flour
salt
1 stick plus 1 tablespoon cold unsalted butter
1/4 c. cold water
3 tbsp. extra-virgin olive oil
4 onions
2 tsp. coarsely chopped fresh thyme
Freshly ground pepper
3 oz. creamy blue cheese
Preparation
Step 1In a food processor, pulse the flour with 1/2 teaspoon of the salt. Add the diced butter and pulse until it’s the size of small peas. Sprinkle in the cold water and pulse again until the tart dough begins to come together. Turn the dough out onto a sheet of plastic wrap and pat it into a disk. Wrap the dough and refrigerate until it is firm, at least 1 hour.Step 2Preheat the oven to 400 degrees F. Meanwhile, in a large skillet, heat the oil. Add the onions and cook over moderate heat, stirring occasionally, until soft and lightly golden, about 25 minutes. Reduce the heat to low and continue to cook, stirring occasionally, until the onions are golden, about 15 minutes longer. Stir in the thyme and season with salt and pepper. Remove from the heat and let the onions cool to room temperature.Step 3On a lightly floured work surface, roll out the dough to a 12-inch round. Wrap the dough around the rolling pin and transfer it to a 10-inch fluted tart pan with a removable bottom. Press the dough into the pan and trim off any excess. Use the scraps to patch any cracks. Prick holes all over the bottom of the crust with a fork. Bake until the crust is lightly browned, about 20 minutes.Step 4Spread the onions in the tart shell and sprinkle with the blue cheese. Bake until the cheese is melted and the onions are warm, about 5 minutes. Cut the tart into wedges and serve.Step 5Make Ahead: The tart can be made up to 4 hours ahead and kept covered at room temperature. Serve at room temperature or rewarm in a 350 degrees F oven.
