How to Make the Perfect Caramelized Onion and Gruyere Tart
French · Medium · 90 min · 6 servings
This elegant savory tart features deeply caramelized golden onions and nutty Gruyere cheese nestled in a flaky buttery pastry shell. It is a show stopping fall appetizer or light meal that is much easier to make than it appears.
Why this recipe works
This Caramelized Onion and Gruyere Tart recipe has been crafted to deliver restaurant-quality results in your home kitchen. At just 90 minutes from start to finish, it fits perfectly into a busy schedule without sacrificing flavor. Each serving comes in at 420 calories with 12g of protein, making it a balanced choice for any meal.
What you will need
This recipe uses 6 simple ingredients that you can find at any grocery store:
- 4 large yellow onions thinly sliced
- 3 tablespoons unsalted butter
- 1.5 cups Gruyere cheese grated
- 1 sheet refrigerated pie dough or puff pastry
- 3 large eggs lightly beaten
- 0.5 cup heavy cream
Step by step instructions
Step 1: Caramelize the Onions
Melt the butter in a large heavy bottomed skillet over medium low heat. Add all the sliced onions with a pinch of salt and stir to coat them in the butter. Cook slowly, stirring every 5 to 7 minutes, for 45 to 55 minutes until the onions are deeply golden brown, very soft, and reduced dramatically in volume. Do not rush this step by raising the heat.
Step 2: Prepare the Tart Shell
Preheat your oven to 375 degrees Fahrenheit. Press the pie dough or puff pastry into a 9 inch tart pan with a removable bottom, trimming any excess overhang. Line the pastry with parchment paper and fill it with pie weights or dried beans. Blind bake for 15 minutes then remove the weights and bake for another 5 minutes until lightly golden.
Step 3: Make the Custard Filling
In a medium bowl whisk together the beaten eggs and heavy cream until smooth and uniform. Season generously with salt, pepper, and a pinch of freshly grated nutmeg if desired. Stir in half of the grated Gruyere cheese. Spread the caramelized onions evenly over the pre baked tart shell and pour the egg and cream custard mixture on top.
Step 4: Top and Bake
Scatter the remaining Gruyere cheese evenly over the top of the tart. Bake at 375 degrees Fahrenheit for 25 to 30 minutes until the custard is just set with a very slight wobble in the center and the top is beautifully golden. Allow the tart to rest for at least 10 minutes before slicing and serving warm or at room temperature.
Easy substitutions
Missing an ingredient? Here are some swaps that work perfectly:
- Gruyere cheese → Swiss cheese or aged white cheddar for a more accessible option
- heavy cream → half and half for a slightly lighter custard
Common mistakes to avoid
Watch out for these pitfalls that can affect your results:
- Rushing the caramelization process by cooking the onions on high heat which burns them and produces a bitter flavor instead of sweet
- Pouring the custard into a hot shell immediately after blind baking which can cause the pastry base to become soggy
Nutrition facts
Per serving: 420 calories, 12g protein, 28g carbs, 30g fat, 2g fiber.
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