Heat the olive oil in a large skillet over medium heat. Add the chopped onion, green onions, and garlic, then cook for about 3 minutes until softened.

Add the spinach in handfuls, letting each batch wilt before adding more. This should take about 2 minutes. Stir in the lemon juice.

Transfer the cooked spinach mixture to a colander and let it cool slightly. Squeeze out as much liquid as you can, using a clean towel if needed.

In a bowl, beat the eggs with the feta cheese, ground coriander, and nutmeg. Season with salt and pepper, then fold in the cooled spinach mixture.

Preheat the oven to 350°F and butter 2 baking sheets. Keep the phyllo covered with a damp towel while you work.

Lay one sheet of phyllo on the counter, brush it with melted butter, and sprinkle on some oregano and chives. Stack two more sheets on top, brushing each with butter as you go.

Cut the stack lengthwise into 3 equal strips. Place a heaping teaspoon of filling at the bottom of each strip, fold the corner over to form a triangle, and keep folding up the strip like a flag.

Brush the top with butter, dust with Parmesan, and place each triangle seam-side down on the baking sheet.

Bake for 20 to 30 minutes, or until the triangles are crisp and deep golden brown. Serve hot, warm, or at room temperature.