Caramelized Onion and Gruyere Cheese Tart
I know I have written before of another person in my life who made a huge impact on my culinary journey. During the late 1970's I worked with a French Chef in Marin County and he taught me many things. Among the list is this tart. He made it mainly for family meals which were served prior to the restaurant opening for dinner. It's very easy to make if using store bought puff pastry and a bit more time consuming if making your own. One just must be patient as the slow caramelization of the onions does take time and attention. If you are going to use premade pastry dough, I think Dufour Classic is by far the best and Pepperidge is not bad and less expensive. The tart is perfect for a light lunch served along with a salad, a first course or how I prefer, cut into small slices or squares and served as an hors d'oeuvre.
Ingredients
- 1 sheet of puff pastry – approximately 9.5"x10.5"
- 4 cups sliced yellow onions (650g)
- 1 tbsp olive oil (8g)
- 2 tbsp butter (28.5g)
- 1 tsp salt (6g)
- 1/4 tsp each ground nutmeg and black pepper (1g)
- 2 egg yolks
- 1/2 cup whipping cream (120g)
- 1 cup grated gruyere cheese(100g)
- 1 tbsp Dijon mustard (15g)
- 2 tbsp grated gruyere to sprinkle on the top prior to baking
Instructions
- Several size and shapes of tart pans will work for this. I have used all three shown here as well as lining a baking sheet with parchment and making a freeform tart. The sizes are 13"x4", 11"x7" and a 9" round.If you are buying your puff pastry the sheets are generally 9.5"x10.5" and can be rolled out to fit a variety of shapes.
- Roll the puff pastry out to fit a removable bottom tart pan of your choice. The sheet of puff pastry should be large enough to form a rim of 3/4" to 1". Once rolled out, place the tart pan in the refrigerator to keep it chilled and firm.
- Peel and slice the onions. They should be about 1/4" or less in thickness. You may find a Mandolin or the slicing attachment to your food processor an easy way to accomplish this.
- Heat the butter and oil in a large sauté pan. A 12" pan is a great size for this. Add the onions, salt, pepper and nutmeg. Cook the onions over medium heat. Use a spatula to gently flip the onions about every 5 minutes to insure they are evenly turning a rich golden brown. If they are getting too dark, reduce the heat. It takes 40 to 45 minutes to achieve a rich golden brown.
- Preheat your oven to 375°
- Set the onions aside for a bit to cool. Mix the egg yolks and cream together. Once the onions have cooled a bit, stir in the egg yolk and cream mixture along with the grated gruyere.
- Remove the puff pastry from the refrigerator and using the back of a spoon or a pastry brush, coat the bottom with the Dijon mustard.
- Spoon the onion mixture into the tart pan. Smooth to cover evenly and sprinkle the top with the 2 tablespoons of grated gruyere.
- Place the tart on the bottom rack of your preheated oven and bake 40 minutes or until golden brown. After 10 minutes remove from the pan and place on a cooling rack.
- Tart may be served hot and straight from the oven, or later at room temperature or slightly warm. You may also reheat by placing on a baking sheet and heated at 375° for 6 to 8 minutes. I do not recommend microwave as it will make the puff pastry crust soft.