Makes 12 servings
3 tablespoons extra-virgin olive oil, Greek or another good-quality, fruity variety preferred
1/2 large Spanish or yellow onion, peeled and chopped into 1/2-inch pieces (about 1 cup)
1 shallot, peeled and diced (about 2 tablespoons)
6 cloves garlic, peeled, cut in half and grated, any green centers discarded
Juice and zest of 1 lemon
2 pounds baby spinach, roughly chopped, any thick stems removed
4 to 6 fronds fresh dill, finely chopped (about 2 teaspoons)
Leaves of 3 sprigs fresh marjoram or oregano, chopped (about 2 teaspoons)
Leaves of 3 sprigs fresh thyme, chopped (about 2 teaspoons)
12 ounces (2 cups) crumbled feta cheese
7 large eggs, lightly beaten
For the crust:
1 cup (2 sticks) salted butter
1/4 cup extra-virgin olive oil, Greek or another good-quality fruity variety preferred
6 dried or 3 fresh bay leaves
1/2 pound frozen filo dough, defrosted in the refrigerator
9×13-inch lasagna pan or large rectangular baking dish
Moistened paper towels
1. To make the filling: Heat the oil in a large saucepan set over high heat until it shimmers. Add the onions and cook, stirring, until they are soft and translucent, 3 to 5 minutes. Add the shallots and cook, stirring, until they have softened, 2 to 3 minutes. Add the garlic, stir well, and cook for 15 seconds. Add the lemon juice and zest and stir to incorporate.
2. Add the spinach: Add as many of the spinach leaves as the pan can hold, and cook, spooning the hot onion mixture over the leaves until they are fully wilted and very dark green in color, 4 to 5 minutes. Repeat the process, working in batches, until all the spinach is fully wilted. Cook the spinach until it has released its liquid and the liquid has evaporated. Remove from the heat and transfer to a large mixing bowl.
3. Add the herbs and cheese: Add the dill, marjoram, and thyme and mix well. Add the feta and mix well. Once the mixture is no longer piping hot, add the eggs and mix well. Set aside.
4. Make the infused butter: Heat the butter and oil in a small saucepan set over medium heat. Add the bay leaves. As soon as the butter is melted, reduce the heat to a simmer and cook for 5 minutes. Remove from the heat and steep the bay leaves for 5 minutes.
5. Prep the filo: Remove the filo dough sheets from their plastic wrapper, unroll on a work surface or plate, and cover with a piece of parchment paper. Drape a few moist paper towels over the parchment paper, covering the entire exposed surface of the pile of filo dough.
6. Build the first layer of the filo crust: Carefully peel 1 sheet of filo from the pile; be sure to replace the parchment and paper towel while you work with this sheet. Place it into the prepared baking dish positioning one end in the center of the pan and letting the sheet drape out over one of the long sides of the pan with about a 3-inch overhang. Peel another sheet from the pile, replace the covering, and place the filo into the pan, next to the first sheet of filo, overlapping it slightly. Repeat, arranging a total of 6 sheets around the entire pan: Two on each long side and one each for the short sides. With a pastry brush, gently dab the some of the melted butter all over the surface of the filo, including the overhang, holding the filo gently with your hand. Don’t worry if some breaks off.
7. Build the second layer of the filo crust: Arrange another layer of 6 sheets on top of the first layer, following the instructions in step 6. (You will have used a total of 12 sheets.) Brush with butter again.
8. Add the filling: Spoon the filling into the crust. Use a silicone spatula to spread it evenly and smooth the top. Make sure to spread the filling into the corners.
9. Begin sealing the pie: Fold the filo overhang up and onto the filling, beginning with the pieces on the long sides of the pan and finishing with the pieces on the short sides. You might find that some of the pieces break in the folding; you can simply place these pieces on top of the filling as if they had been folded. Other pieces might resist your attempt at folding. Use kitchen shears to cut these and fit them into the pan if needed.
10. Build the top crust: Carefully peel 1 sheet of filo from the pile and again replace the covering of paper towel. Place this sheet of filo lengthwise on top of the filling and tuck the edges into the sides. With a pastry brush, gently dab some of the melted butter all over it. Top with another sheet and brush with butter again. Repeat with 2 more sheets, brushing each with butter. Then place 2 sheets on at a time and dab the surface liberally with the butter. Repeat until you have used up a total of 8 sheets.
11. Bake the spanakopita: Bake for 45 to 50 minutes or until the top is golden-brown and crispy. Serve immediately.