A slice of this tart with a mixed greens salad with a nice vinaigrette is my go-to lunch for the girls. Add a sliver of fudge pie and it’s perfect. It’s elegant, easy, impressive, and delicious! What more can you ask for? Want a fork?
1 sheet puff pastry, thawed
2 tablespoons oil
2 tablespoons butter
2 medium sweet yellow onions, peeled and thinly sliced
1 clove garlic, peeled and minced
1/2 teaspoon sea salt
1/2 teaspoon sugar
1/2 teaspoon fresh ground black pepper
1/2 cup heavy cream
1 extra-large egg
1 cup fresh shredded Swiss cheese
3 tablespoons fresh grated Parmesan cheese
Preheat oven to 375 degrees. Butter a baking sheet pan. Roll thawed sheet of pastry to fit your pan. Poke bottom of crust with a fork. Cut a piece of foil or parchment paper that is bigger than your pan. Lay this over the puff pastry crust, allowing plenty of overhang. Fill with baking weights, dried beans or rice to weigh it down. Bake for 25-30 minutes. Remove from oven; remove the weights and allow pastry to cool.
In a large nonstick saucepan, melt butter together with oil on low-medium heat. Add the sliced onions, salt, pepper, sugar, and thyme. Allow them to come to a very low simmer, stirring occasionally, and cook for about 20 minutes until they are very soft, and slightly caramelized, but not browned. Add garlic and cook an additional 2 minutes, stirring. Set aside to cool.
In a medium bowl, whisk egg, stir in cream and shredded Swiss cheese. Stir in the cooled cooked onion mixture and pour onto the cooled crust, spreading evenly. Sprinkle the Parmesan over the filling.
Bake for 20-25 minutes or until filling is set and golden. Cool for 5 minutes. Serve hot, warm or at room temperature.