How to Make It
Preheat the oven to 400°. In a small skillet, heat the olive oil until shimmering. Add the onion and garlic and cook over high heat until softened, about 5 minutes. Transfer to a large bowl. Add the spinach, bread crumbs, dill, oregano, lemon juice, egg, nutmeg, 1 teaspoon of kosher salt and 1/4 teaspoon of pepper. Stir in the feta and mix well.
Arrange one sheet of phyllo on a work surface with a long side facing you. Brush generously with some of the melted butter. Layer the remaining four sheets of phyllo on top, brushing each sheet with butter. Mound the spinach mixture along the bottom edge of the phyllo and roll as tightly as possible. Slide the log onto a parchment paper–lined baking sheet and brush with the remaining melted butter.
Bake the spanakopita in the upper third of the oven for 30 minutes, until golden and crisp. Slide the spanakopita onto a cutting board and slice into 4 pieces. Serve hot or at room temperature.