It takes a little while for the onions to caramelize, so start them first. Like many quiches, this can be frozen unbaked and then baked without thawing, so while you’re at it, why not make two?
1/2 14 ounce box refrigerated pie crust (1 crust)
For the caramelized onions:
1 pound Vidalia onions, sliced
2 tsp olive oil
2 tsp butter
1 pinch salt
For the filling:
1 Tbsp olive oil
1 1/2 pounds zucchini, sliced 1/8″ thick
2 cloves garlic clove, minced
3/4 ts kosher salt, divided
1/4 cup heavy cream
1/2 cup milk
1/2 tsp black pepper
3 extra large eggs
3 oz Parmesan cheese, grated
1. Preheat oven to 425°.
2. On a lightly floured square of foil, roll dough into a 12″ circle. Reserve the foil to shield the edges of the crust. Fit the dough into a 10″ deep-dish pie pan. Fold the edges of the crust under and flute. Dock by pricking all over with a fork. On a foil lined cookie sheet, bake the crust for 12 minutes or until it is just beginning to brown. Set aside to cool.
3. Reduce the oven to 375°.
4. For the caramelized onions: In a large sauce pan over medium heat, melt together the butter and olive oil. Add the sliced onions and stir to coat. Season with a pinch of salt, cover, and reduce the heat to medium low. Cook, stirring occasionally, until very soft. If the onions begin to brown before they are softened reduce the heat further. When the onions are very soft, uncover and continue to cook stirring very frequently. If the onions begin to stick add a tablespoon or two of water. As the onions begin to caramelize you will need to stir more often, almost constantly towards the end. Cook the onions until they are the color of a new copper penny, then remove from heat. Spread the onions in the bottom of the baked pie crust.
5 .For the filling: In a large non-stick skillet over medium heat, warm th oilive oil until very hot. Add the zucchini and season with 1/4 tsp salt. Stir fry 5 minutes or until tender crisp. Add the garlic and cook 1 minute longer, or until fragrant. Spread over the onions in the pie crust.
6. In a medium bowl, combine the rest of the salt and all the remaining ingredients. Whisk together well and pour over the zucchini.
7. Bake on the cookie sheet for 20 minutes. While the quiche is baking, fold the reserved piece of foil into quarters. About 4″ from the folded point tear a semi-circle out of the foil. This will give you a shield with an open center to cover the edges of the crust. Cover the edges of the crust and continue to bake another 30 minutes, or until set. Let stand 10 minutes before serving.