For the Herb and Cheese Filling:
8 ounces (225g) Greek feta, crumbled
4 ounces (115g) Muenster or Monterey Jack cheese, shredded
2 1/2 ounces (70g) fresh goat cheese, crumbled
1/2 cup chopped mixed tender herbs and tender stems (about 2 ounces; 60g), such as dill, parsley, mint, and cilantro
4 scallions (2 ounces; 60g), thinly sliced (1/2 cup)
2 large eggs (110g), lightly beaten
1/4 teaspoon freshly ground black pepper
For the Spinach, Herb, and Cheese Filling:
10 ounces (285g) frozen chopped spinach, thawed
8 ounces (225g) Greek feta, crumbled
2 1/2 ounces (70g) fresh goat cheese, crumbled
2 ounces (1 packed cup; 60g) chopped mixed tender herbs and tender stems, such as dill, parsley, mint, and cilantro (about 2 packed cups picked herbs before chopping)
4 scallions (2 ounces; 60g), thinly sliced (1/2 cup)
2 large eggs (110g), lightly beaten
1/4 teaspoon Diamond Crystal kosher salt; for table salt use half as much by volume
1/4 teaspoon freshly ground black pepper
For the Boreks:
9 (13- by 18-inch) sheets phyllo dough, thawed and rested at room temperature for 30 minutes
10 tablespoons (5 ounces; 140g) unsalted butter
1 tablespoon hulled sesame seeds
1 teaspoon nigella seeds (optional; see notes)
