Back on Christmas Eve 2007, our family enjoyed this delicious caramelized onion and Gruyère tart for the first time. We’ve made this tart a few times since then, and have always enjoyed it. The rich flavors of the caramelized onions and Gruyère cheese are superb together! 😋 The egg-and-cream mixture in the filling reminds me of a quiche, but this tart has more onions and cheese than eggs.
This caramelized onion and Gruyère tart is a fantastic addition to a brunch menu, but can also be enjoyed as a light dinner alongside a salad. The recipe makes more onions and herbed cheese than will fit into a 9-inch tart pan, so bake the extra in a little ramekin for a personal-sized tart. It would be perfect for a light lunch the next day!
I encourage you to make this caramelized onion and Gruyère tart during the Christmas holidays or anytime of the year. There’s some work involved, but it’s totally worth every minute!Print
This delicious onion and Gruyère tart is sure to thrill your family and friends with the lovely flavor of caramelized onions, Gruyère cheese, and herbs all inside a flaky pastry crust. Make this easy tart today!
For the Pastry
For the Caramelized Onions
- 1 lb. 13 oz. sweet onions (about 3 large onions)
- 2 tablespoons butter
- 1 large bay leaf
- 1 heaping tablespoon fresh thyme leaves, roughly chopped
- 2 tablespoons white balsamic vinegar
For the Herbed Cheese
- 2 cups Gruyère cheese, grated (about 2 cups)
- 1 tablespoon all-purpose flour
- 1 teaspoon dried rosemary
- 1/2 teaspoon dried parsley
- 1/2 teaspoon marjoram
- 1/2 teaspoon herbes de Provence
- 1/2 teaspoon salt
- 1/4 teaspoon nutmeg
- 1/4 teaspoon white pepper
For the Egg Filling
- 2 large eggs
- 1/2 cup heavy whipping cream
Caramelizing the Onions (10 minutes + 40 minutes cooking)
- Peel, quarter, and thinly slice the onions. Wash and dry a handful of fresh thyme, remove the leaves, and roughly chop them.
- Melt 2 tablespoons of butter in a large skillet over medium-high heat. Add the onions, bay leaf, and thyme and stir to coat with the melted butter.
- Turn the heat down to medium and cook the onions for about 40-45 minutes, stirring frequently. The onions should be very soft and rich golden brown.
- Towards the end of the cooking time, deglaze the pan once or twice with 1 tablespoon of white balsamic vinegar. For more info about caramelizing onions and deglazing the pan, refer to my article here.
- Spoon the onions into a bowl to cool and set aside.
Preparing the Herbed Cheese (10 minutes)
- Grate the block of Gruyère and pour the cheese into a medium bowl.
- Add the flour and spices and toss until well combined. Set aside.
Preparing the Egg Filling (5 minutes)
- Preheat the oven to 425 F and put a metal cookie sheet with sides in to preheat.
- Whisk together the eggs and cream until well blended. Set aside.
Assembling & Baking the Tart (5 minutes + 30 minutes baking + 20 minutes cooling)
- Press three quarters of the herbed cheese into the bottom of the 9-inch, bind baked pastry shell. Evenly top with almost all of the caramelized onions. Pour the egg mixture evenly over the top.
- Set the tart on the preheated cookie sheet and bake at 425 F for 10 minutes. Lower the temperature to 375 F and bake for another 10 minutes. Finally, bake the tart at 300 F for 8 minutes, or until a knife inserted in the center comes out clean.
- Let the tart cool in the pan for 10 minutes, then remove it from the pan and let it cool for another 10 minutes on a wire rack.
- Serve warm.
- Reserve the extra cheese and onions to make a mini tart with leftover pastry. If you don’t have any extra pastry in your fridge, just bake the mini tart in a buttered ramekin without the crust.