Step 1: Heat olive oil in a large skillet over medium heat. Add the chopped onion and sauté until softened and translucent, about 5-7 minutes. Add the minced garlic and cook for another minute until fragrant.
Step 2: Add the fresh spinach to the skillet in batches, if necessary. Cook, stirring frequently, until all the spinach has wilted completely. If using thawed frozen spinach, add it to the skillet to warm through and cook off any remaining moisture.
Step 3: Transfer the cooked spinach mixture to a colander and let it cool slightly. Once cool enough to handle, use your hands or a clean kitchen towel to squeeze out as much excess liquid as possible. This is a critical step for a non-soggy filling!
Step 4: In a large bowl, combine the squeezed spinach, crumbled feta cheese, chopped dill, chopped parsley, lightly beaten eggs, and nutmeg. Season with salt and freshly ground black pepper to taste, keeping in mind that feta is already quite salty. Mix everything thoroughly until well combined. This is your delicious filling.
Step 5: Preheat your oven to 375°F (190°C). Lightly grease a large round baking dish (approximately 9-10 inches). Melt the butter in a small saucepan or microwave-safe bowl.
Step 6: Lay one sheet of phyllo dough on a clean work surface. Brush it lightly with melted butter. Place another sheet directly on top and brush with butter. Repeat this process until you have a stack of 3-4 phyllo sheets, all brushed with butter between layers.
Step 7: Spoon about 1/8 to 1/10 of the spinach and feta filling in a line along one long edge of the phyllo stack, leaving a small border at the ends. Gently roll the phyllo up tightly, creating a long, thin 'rope' of filling.
Step 8: Carefully transfer the phyllo rope to the prepared baking dish, starting from the center and coiling it into a tight spiral. Continue making more phyllo ropes with the remaining filling and phyllo sheets, connecting each new rope to the end of the previous one in the baking dish, until you've formed a complete spiral. Ensure your phyllo remains covered with a damp towel while you work.
Step 9: Once the entire Easy Spanakopita Spiral is assembled in the dish, brush the top generously with any remaining melted butter. This will help achieve that beautiful golden, crispy crust.
Step 10: Bake for 45-55 minutes, or until the phyllo is golden brown and crispy, and the filling is set. If the top starts browning too quickly, you can loosely tent it with aluminum foil.
Step 11: Remove from the oven and let the Easy Spanakopita Spiral rest for 10-15 minutes before slicing and serving. This allows the filling to firm up slightly. Enjoy your magnificent Greek creation!