1/2 cup olive oil
1 bunch chopped scallions, white and green parts
2 (10-ounce) boxes frozen chopped spinach, defrosted
2 tablespoons chopped fresh dill
3 extra-large eggs, lightly beaten
7 ounces feta cheese, crumbled
1/4 teaspoon kosher salt
1/4 teaspoon freshly ground black pepper
40 sheets (1 box) frozen phyllo dough (such as Pepperidge Farm), defrosted overnight in the refrigerator
1/2 pound (2 sticks) unsalted butter, melted
1/2 cup plain dry breadcrumbs