Preheat the oven to 375°F (190°C) and lightly grease a 9-inch round baking pan.
Heat a drizzle of olive oil in a large skillet over medium heat. Sauté the onion until softened, then add the garlic.
Add the spinach, salt, and pepper. Cook until wilted, then stir in the lemon juice. Increase the heat and cook until all excess moisture has evaporated.
Allow the spinach mixture to cool slightly.
In a large bowl, combine the spinach mixture with goat cheese, feta, cheddar, egg, parsley, pine nuts, and nutmeg. Mix until evenly combined.
Lay two sheets of filo pastry on a clean surface and brush lightly with olive oil or melted butter.
Spread about 4 tablespoons of the filling along one long edge, leaving a small border. Roll tightly into a log.
Coil the first log into the center of the prepared pan.
Continue making additional logs and wrap each around the previous coil until the pan is full. This Spanakopita Spiral creates an eye-catching presentation.
Brush the entire top generously with olive oil or melted butter.
Bake for 25–30 minutes until the pastry is deeply golden and crisp.
Let cool for 10 minutes before slicing and serving.