Preheat oven to 375°F (190°C) and grease a 12-inch round baking pan.

Sauté onion in olive oil over medium heat until translucent, then add garlic and cook for 60 seconds.

Add spinach to the pan in batches until wilted; transfer to a colander and squeeze firmly to remove all excess moisture.

In a large bowl, combine the dried spinach, feta cheese, beaten eggs, dill, parsley, nutmeg, and pepper.

Lay one sheet of phyllo on a flat surface, brush with melted butter, and stack a second sheet on top, brushing again with butter.

Distribute a thin line of spinach filling along the long edge of the phyllo sheet.

Roll the phyllo tightly around the filling to create a long cylinder.

Place the cylinder in the center of the baking pan, coiling it into a tight circle.

Repeat the rolling process with remaining ingredients, connecting each new rope to the end of the previous one to expand the spiral.

Brush the surface of the spiral generously with remaining butter and sprinkle with sesame seeds.

Bake for 45 to 50 minutes until the pastry is deep golden brown and crispy.

Allow to rest for 10 minutes before slicing into wedges.