This is a very typical recipe from the Alsace region of France. I made over the weekend for a friend’s mother and she raved about it. Although there are just a few ingredients, it has outstanding flavor - perfect for a Sunday brunch. The secret is slow cooking the onions until they are very soft.f
1 1/4 cups unbleached all-purpose flour (6 1/4 ounces)
1 tablespoon sugar
1/2 teaspoon table salt
8 tablespoons unsalted butter (1 stick), cut into 1/2-inch cubes and well chilled
2 - 3 tablespoons ice water
4 ounces bacon (about 4 slices), halved lengthwise, then cut crosswise into 1/4-inch pieces
1 1/2 pounds yellow or white onions, halved through root end, peeled, and cut crosswise into 1/4-inch slices (about 6 cups)
1 sprig fresh thyme
3/4 teaspoon table salt
Pinch of nutmeg
Pinch of cayenne
2 large eggs
1/2 cup half-and-half
1/4 teaspoon ground white or black pepper
FOR THE CRUST:
1. Spray 9-inch tart pan with nonstick cooking spray. Combine flour, sugar, and salt in food processor with four 1-second pulses. Scatter butter pieces over flour mixture; pulse to cut butter into flour until mixture resembles coarse sand, about fifteen 1-second pulses.
2. Add 2 tablespoons ice water and process until large clumps form and no powdery bits remain, about 5 seconds, adding up to 1 tablespoon more water if dough will not form clumps.
3. Scatter walnut-sized clumps of dough evenly into tart pan. Working outward from the center, press the dough into even layer, sealing any cracks. (Take your time with these steps, it will ensure that the dough does not crack during baking.) Work your way around the edge of tart pan and press the dough firmly into the corners with your index finger. Go around edge once more, pressing dough up sides and into fluted ridges. Use your thumb to level off top edge. Use this dough to patch any holes. Lay plastic wrap over dough and smooth out any bumps or shallow areas
4. Place tart shell on plate and transfer to freezer for 30 minutes.
5. Adjust oven rack to middle position and heat oven to 375 degrees. Place frozen tart shell on baking sheet; lightly spray one side of 18-inch square extra-wide heavy-duty aluminum foil with nonstick cooking spray. Press foil greased side down inside tart shell, folding excess foil over edge of pan. Fill with pie weights and bake until top edge just starts to color and surface of dough under foil no longer looks wet, about 30 minutes. Remove from oven and carefully remove foil and weights by gathering edges of foil and pulling up and out. Return baking sheet with tart shell to oven and bake until golden brown, 5 to 10 minutes. Set baking sheet with tart shell on wire rack. Do not turn off oven.
FOR THE FILLING:
1. While crust is baking, cook bacon in 12-inch nonstick skillet over medium heat until browned and crisp, 8 to 10 minutes. Drain bacon through mesh strainer set over small bowl; transfer bacon to paper towel-lined plate. Return 2 tablespoons bacon fat to skillet, adding vegetable oil to make up difference if necessary.
2. Add onions, salt, nutmeg, cayenne and thyme to skillet. Cover and cook until onions release liquid and start to wilt, about 10 minutes. Reduce heat to low and continue to cook, covered, until onions are very soft, about 20 minutes, stirring once or twice (if after 15 minutes onions look wet, remove lid and continue to cook another 5 minutes). Remove pan from heat and let onions cool 5 minutes.
3. Whisk eggs, half-and-half, and pepper together in large bowl. Remove thyme sprig from onions; discard. Stir onions into egg mixture until just incorporated. Spread onion mixture over baked crust (still on baking sheet) and sprinkle bacon evenly on top.
4. Return baking sheet with tart to oven and bake until center of tart feels firm to touch, 20 to 25 minutes. Cool on wire rack at least 10 minutes. When ready to serve, remove tart pan ring; gently slide thin-bladed spatula between tart pan bottom and crust to loosen, then slide tart to serving plate. Cut into wedges and serve. Leftovers should be wrapped in plastic wrap and refrigerated. Reheat on a baking sheet in a 325-degree oven for 10 to 15 minutes.