72-Hour Slow-Cooked Onion Soubise Quiche with Duck Confit Recipe

Master this homemade gourmet quiche featuring the best slow-cooked onion soubise and tender duck confit. This easy baking recipe transforms humble ingredients into a showstopping dish through patient cooking techniques that develop extraordinary depth of flavor – perfect for impressing guests or elevating weekend brunch.

Difficulty:

Advanced

Prep Time:

2 hours 30 mins

Cook Time:

73 hours 45 mins

Serves:

1 quiche (8 slices)

Ingredients

<ul class="ingredients-main-list"><li class="ingredients-single-item">For the Duck Confit:</li><li class="ingredients-single-item">4 duck leg quarters (about 1kg)</li><li class="ingredients-single-item">25g sea salt</li><li class="ingredients-single-item">4 sprigs fresh thyme</li><li class="ingredients-single-item">2 bay leaves</li><li class="ingredients-single-item">4 garlic cloves, crushed</li><li class="ingredients-single-item">1 tsp black peppercorns, crushed</li><li class="ingredients-single-item">500g duck fat (or goose fat)</li><li class="ingredients-single-item">For the Onion Soubise:</li><li class="ingredients-single-item">1.5kg sweet onions, thinly sliced</li><li class="ingredients-single-item">150g unsalted butter</li><li class="ingredients-single-item">100ml dry white wine</li><li class="ingredients-single-item">250ml heavy cream</li><li class="ingredients-single-item">2 sprigs fresh thyme</li><li class="ingredients-single-item">1/2 tsp freshly grated nutmeg</li><li class="ingredients-single-item">Salt and white pepper to taste</li><li class="ingredients-single-item">For the Pastry:</li><li class="ingredients-single-item">300g all-purpose flour</li><li class="ingredients-single-item">150g cold unsalted butter, cubed</li><li class="ingredients-single-item">1 tsp salt</li><li class="ingredients-single-item">1 large egg</li><li class="ingredients-single-item">2-3 tbsp ice-cold water</li><li class="ingredients-single-item">For the Quiche Filling:</li><li class="ingredients-single-item">5 large eggs</li><li class="ingredients-single-item">250ml heavy cream</li><li class="ingredients-single-item">100ml whole milk</li><li class="ingredients-single-item">100g Gruyère cheese, grated (or Comté)</li><li class="ingredients-single-item">2 tbsp fresh thyme leaves</li><li class="ingredients-single-item">Pinch of freshly grated nutmeg</li><li class="ingredients-single-item">Salt and freshly ground black pepper</li></ul>

Equipment

<ul class="equipment-main-list"><li class="equipment-single-item">25cm (10-inch) deep quiche or tart pan with removable bottom</li><li class="equipment-single-item">Slow cooker or Dutch oven</li><li class="equipment-single-item">Food processor</li><li class="equipment-single-item">Ceramic baking beans</li><li class="equipment-single-item">Digital kitchen thermometer</li><li class="equipment-single-item">Mandoline slicer (for onions)</li><li class="equipment-single-item">Cheesecloth</li></ul>

Directions

<ol class="no-list-style"><li class="MethodStepper"><h4 class="step-title">Step 1</h4>Begin with the duck confit 3 days before serving. Combine salt, crushed peppercorns, thyme leaves, and crushed garlic in a small bowl. Rub this mixture thoroughly all over the duck legs, place in a shallow dish, cover with plastic wrap and refrigerate for 24 hours. This curing process draws moisture from the duck, concentrating flavors and helping preserve the meat.</li><li class="MethodStepper"><h4 class="step-title">Step 2</h4>After 24 hours, rinse the duck legs thoroughly under cold water to remove the salt mixture, then pat completely dry with paper towels. Preheat your oven to 110°C. Place the duck legs in a Dutch oven or ovenproof dish and cover completely with the duck fat. The fat must completely submerge the meat to create an oxygen-free environment that prevents bacterial growth while slowly cooking.</li><li class="MethodStepper"><h4 class="step-title">Step 3</h4>Cover the Dutch oven and place in the preheated oven. Cook at this very low temperature for 8-10 hours until the meat is extremely tender but not falling apart. The collagen in the duck legs slowly converts to gelatin at this temperature, resulting in supremely tender meat. Remove from oven and allow to cool completely while still submerged in the fat.</li><li class="MethodStepper"><h4 class="step-title">Step 4</h4>For the onion soubise, begin 3 days before serving. Using a mandoline, thinly slice all onions to ensure even cooking. Melt the butter in a large heavy-bottomed pot over medium-low heat. Add the onions, reduce heat to low, and cook uncovered for 1 hour, stirring occasionally until they begin to soften without coloring.</li><li class="MethodStepper"><h4 class="step-title">Step 5</h4>Add the white wine, thyme sprigs, and a pinch of salt to the onions. Cover the pot and reduce heat to the lowest possible setting. Cook for 48 hours, stirring occasionally, checking that the onions remain moist (add a tablespoon of water if needed). The extremely slow cooking breaks down the onions' cell walls completely while preventing caramelization, creating a uniquely sweet, complex flavor without browning.</li><li class="MethodStepper"><h4 class="step-title">Step 6</h4>After 48 hours, remove the thyme sprigs from the onions and add the heavy cream. Continue cooking uncovered on low heat for another 12 hours, stirring occasionally until the mixture has reduced to a thick, silky consistency. Season with nutmeg, salt, and white pepper. The mixture should be pale ivory in color and intensely flavorful. Transfer to a food processor and blend until completely smooth. Pass through a fine-mesh sieve and set aside.</li><li class="MethodStepper"><h4 class="step-title">Step 7</h4>One day before serving, make the pastry. In a food processor, combine flour and salt with short pulses. Add the cold cubed butter and pulse until the mixture resembles coarse breadcrumbs (this keeps the pastry flaky by creating small pockets of butter). Beat the egg with 2 tablespoons of ice water, then add to the processor and pulse just until the dough begins to come together. If too dry, add the remaining tablespoon of water.</li><li class="MethodStepper"><h4 class="step-title">Step 8</h4>Turn the dough onto a lightly floured surface, form into a disk without overworking (which develops gluten and makes tough pastry), wrap in plastic, and refrigerate for at least 2 hours or overnight. Cold dough relaxes the gluten and firms the butter, ensuring a better bake.</li><li class="MethodStepper"><h4 class="step-title">Step 9</h4>On baking day, remove the duck legs from the fat, scraping excess fat back into the container (the remaining fat can be strained and refrigerated for future use). Shred the meat using two forks, discarding skin and bones. The meat should be richly flavored and tender.</li><li class="MethodStepper"><h4 class="step-title">Step 10</h4>Preheat your oven to 190°C. Roll out the chilled pastry on a lightly floured surface to a 30cm circle, about 3-4mm thick. Carefully drape over the quiche pan, pressing gently into the corners without stretching. Trim excess leaving a 1cm overhang, then fold this overhang inward and crimp decoratively. The overhang compensates for pastry shrinkage during baking.</li><li class="MethodStepper"><h4 class="step-title">Step 11</h4>Line the pastry case with parchment paper and fill with ceramic baking beans or dried beans. Blind bake for 15 minutes, then remove the paper and beans and bake for another 5-7 minutes until the base is dry and just beginning to color. This prevents the dreaded "soggy bottom" by creating a moisture barrier.</li><li class="MethodStepper"><h4 class="step-title">Step 12</h4>Reduce oven temperature to 170°C. Spread an even layer of onion soubise (about 400g) on the bottom of the pastry case. Distribute the shredded duck confit evenly over the soubise and sprinkle with half the grated Gruyère cheese.</li><li class="MethodStepper"><h4 class="step-title">Step 13</h4>In a bowl, whisk together eggs, cream, milk, thyme leaves, remaining cheese, nutmeg, salt, and pepper until well combined. Carefully pour this mixture over the duck and soubise in the pastry case. The custard should come just below the rim of the pastry.</li><li class="MethodStepper"><h4 class="step-title">Step 14</h4>Bake the quiche for 35-40 minutes until the filling is just set but still has a slight wobble in the center when gently shaken. The internal temperature should reach 72-74°C. A gentle bake ensures a silky texture rather than a rubbery one. If the pastry edges brown too quickly, cover them with foil.</li><li class="MethodStepper"><h4 class="step-title">Step 15</h4>Allow the quiche to cool for at least 30 minutes before removing from the pan and slicing. This resting period allows the proteins to set fully while retaining moisture. Serve warm or at room temperature with a small dollop of the remaining soubise on the side and a lightly dressed salad of bitter greens to balance the richness. Savor each bite of this labor of love – a true testament to the magic of slow cooking and patience in the kitchen.</li></ol>

FAQs

Find answers to your most pressing questions about this delicious recipe right here.

What ingredients are used in 72-Hour Slow-Cooked Onion Soubise Quiche with Duck Confit Recipe?

The recipe requires duck legs, sea salt, herbs, duck fat, sweet onions, butter, white wine, cream, flour, eggs, Gruyère cheese, and seasonings. The key components are the duck confit, slow-cooked onion soubise, and a buttery pastry case.

How to cook 72-Hour Slow-Cooked Onion Soubise Quiche with Duck Confit Recipe at home?

Learn how to cook 72-Hour Slow-Cooked Onion Soubise Quiche with Duck Confit by following a three-stage process: first, cure and slow-cook duck legs in fat for 8-10 hours; next, prepare onion soubise by cooking sliced onions for 48 hours until silky; finally, blind-bake pastry and assemble with the duck, soubise, and egg custard before baking until set but slightly wobbly.

Can I make a quicker version of the onion soubise for this gourmet quiche?

Yes, though the depth of flavour won't be identical, you can create a faster version by caramelising onions for 1-2 hours with butter until very soft, then adding cream and blending until smooth. The texture will be similar but the complex sweetness that develops over 72 hours will be less pronounced.

What wine pairs best with duck confit quiche?

A medium-bodied red wine with good acidity works beautifully, such as Pinot Noir, Beaujolais, or a Loire Valley Cabernet Franc. For white wine enthusiasts, try an aged white Burgundy or rich Alsatian Pinot Gris that can stand up to the quiche's luxurious richness and complex flavours.

Why is blind baking the pastry case essential for a perfect quiche?

Blind baking creates a moisture barrier that prevents the wet filling from making the pastry soggy. By pre-cooking the pastry case, you ensure a crisp, flaky texture that contrasts beautifully with the silky filling. This technique is particularly crucial for custard-based tarts like this luxurious duck confit quiche.

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