Spanakopita

Name: Spanakopita
Cuisine: Greek, Italian, Mediterranean, European
Ingredients: 1 1/4 pounds (20 ounces or 565 grams) baby spinach [see Note about frozen], roughly chopped; 1 cup red onion (from 1 small or half a large), finely chopped; 6 to 8 scallions (about 2.25 ounces or 65 grams) scallions thinly sliced; 2 cloves garlic, minced; 1/3 cup chopped fresh dill, or more to taste; 1/3 cup chopped fresh mint, or more to taste; 1/2 cup chopped fresh parsley; 3/4 pound (12 ounces or 340 grams) feta, drained, crumbled; 1 large egg; Kosher salt and freshly ground black pepper; 1-pound (454-gram) package phyllo/filo pastry, defrosted [see Note]; Olive oil