Caramelized Onion and Blue Cheese Tart: Bold, Elegant, and Full of Flavor

The Caramelized Onion and Blue Cheese Tart is where rustic simplicity meets rich sophistication. This tart blends the mellow sweetness of slow-cooked onions with the bold tang of blue cheese, all nestled in a crisp, buttery crust. It’s a dish that commands attention despite its minimal ingredients—perfect for entertaining, serving as a dinner party appetizer, a brunch centerpiece, or even a light, luxurious lunch.

Caramelized onions bring natural depth and a silky texture, while the blue cheese adds contrast with its sharp, salty bite. The marriage of these two powerful ingredients creates a dish that feels balanced, comforting, and just a bit indulgent. Serve it warm with a crisp salad or slice it into thin wedges for a sophisticated hors d’oeuvre. Either way, this tart makes a strong impression with very little effort.

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Ingredients

This recipe makes one 9-inch tart, serving 6–8 as a starter or light main.

Ingredient	Quantity
Tart shell (store-bought or homemade, blind-baked)	1 (9-inch)
Yellow onions (thinly sliced)	3 large
Olive oil	1 tablespoon
Butter	1 tablespoon
Salt	½ teaspoon
Fresh thyme (optional)	1 teaspoon (chopped)
Heavy cream	¾ cup
Eggs	2 large
Blue cheese (crumbled)	½ cup (about 3–4 oz)
Black pepper	To taste

Ingredient Notes:

• Onions: Yellow or sweet onions work best. Slice them as evenly as possible for uniform caramelization.
• Blue cheese: Choose a bold, creamy variety like Gorgonzola, Roquefort, or Danish Blue. Goat cheese can be swapped for a milder version.
• Crust: A classic pie crust offers sturdiness; a shortcrust pastry adds richness and texture.

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Equipment Needed

All you’ll need to execute this tart flawlessly:

• 9-inch tart pan: Preferably with a removable bottom for easy slicing and presentation.
• Heavy skillet: For caramelizing the onions evenly.
• Mixing bowl and whisk: For combining the custard base.
• Pie weights or beans: For blind baking the tart shell if making from scratch.
• Baking sheet: To catch any drips and help with even heating.

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Step-by-Step Instructions

Step 1: Caramelize the Onions

In a large skillet, heat the olive oil and butter over medium-low heat. Add the sliced onions and a pinch of salt. Stir occasionally and cook for 30–40 minutes, until the onions are soft, golden brown, and deeply caramelized. If they start to brown too quickly, reduce the heat.

Toward the end of cooking, add the thyme if using. Let the onions cool slightly before adding to the tart shell.

Step 2: Preheat and Prepare

Preheat your oven to 375°F (190°C).

If you’re using homemade dough, blind bake the tart shell for 10–15 minutes with pie weights, then remove weights and bake for an additional 5 minutes until lightly golden. Let cool.

Step 3: Assemble the Tart

In a mixing bowl, whisk together the eggs, heavy cream, and a pinch of black pepper. Gently stir in half of the blue cheese.

Spread the caramelized onions evenly in the tart shell. Pour the egg mixture over the onions. Sprinkle the remaining blue cheese over the top.

Step 4: Bake

Place the tart on a baking sheet and bake for 30–35 minutes, or until the custard is set and the top is lightly golden. The tart should have a slight wobble in the center but no visible liquid.

Let cool for 10–15 minutes before slicing. Serve warm or at room temperature.

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Tips and Variations

• Enhance the onions: Deglaze the skillet with a splash of balsamic vinegar or white wine for deeper flavor.
• Milder cheese: Try brie or fontina for a creamier, less assertive result.
• Make it gluten-free: Use a gluten-free tart shell or crust alternative.
• Add protein: Crumbled bacon or pancetta pairs beautifully with the onions and cheese.
• Make ahead: Caramelize the onions a day ahead and refrigerate. The tart can also be baked in advance and reheated.

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Serving Suggestions

Serve this tart in slices alongside:

• A bitter greens salad with mustard vinaigrette
• Roasted root vegetables for a hearty meal
• A light soup like butternut squash or tomato basil

For presentation, garnish with a few fresh thyme leaves or a light drizzle of honey to offset the sharpness of the blue cheese.

This tart also makes an elegant party appetizer when sliced into thin wedges or squares and served on a wooden board with crackers and nuts.

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Pairings

• Wine: Try a crisp Sauvignon Blanc, a dry Riesling, or a light Pinot Noir to balance the richness.
• Beer: A Belgian-style ale or a hoppy pale ale complements the sharp cheese and sweet onions.
• Cocktail: Consider a dry martini with a lemon twist or a gin and elderflower spritz.
• Non-alcoholic: A chilled sparkling apple cider or iced hibiscus tea works wonderfully.

These drinks add brightness and contrast to the creamy, savory filling.

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Storage and Reheating

• Refrigerator: Store cooled slices in an airtight container for up to 3 days.
• Freezer: Wrap tightly in foil and freeze for up to 1 month. Thaw overnight in the fridge.
• Reheating: Warm in a 325°F oven for 10–12 minutes until heated through. Avoid microwaving, which can affect the crust’s texture.

This tart tastes great both freshly baked and as leftovers, making it ideal for meal prep or entertaining.

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Nutritional Information (Per Serving, Based on 8 Servings)

• Calories: ~280
• Fat: 20g
• Carbohydrates: 15g
• Protein: 8g
• Allergens: Dairy, eggs, gluten (if not using a GF crust)

Nutrition information is automatically calculated, so should only be used as an approximation.

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Conclusion

Caramelized Onion and Blue Cheese Tart is a savory showstopper that manages to be both rich and refined. The depth of the onions, the boldness of the cheese, and the flakiness of the crust all work together to create a dish that’s full of contrast and character.

Perfect for brunches, lunches, or even a light dinner, this tart welcomes experimentation and impresses every time. Try it as written, or give it your own spin—and don’t forget to share your results!

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