In a medium pan, heat oil over medium-high heat.

Add onion and sauté until golden, about eight minutes.

Add garlic and cook until fragrant, about one minute.

Remove from heat and transfer to a bowl.

Return pan to heat.

Working in batches, cook spinach, tossing until wilted, about one minute.

Drain spinach and let cool.

Squeeze out excess moisture, then chop roughly.

Add spinach, feta cheese, and raisins  to the bowl with the onion, and season with salt, pepper, and nutmeg.

Preheat oven to 350 degrees Fahrenheit.

Unroll phyllo dough, place one sheet on a work surface (keep remaining sheets covered with a damp kitchen towel to prevent drying), and brush with oil.

Lay another sheet on top and brush with oil.

Repeat until you have ten layers of phyllo.

Spread half of filling lengthwise down the middle of the phyllo stack.

Roll into a log, brushing the seam with oil before sealing.

Brush log with oil.

Using a small, sharp knife, make eight shallow diagonal cuts on top.

Repeat with remaining phyllo and filling.

Place logs seam-side down on a Gefen Easy Baking Parchment-lined baking sheet.

Bake until deep golden brown, about 45–50 minutes.

Cut into slices along the slashes.

Serve warm or at room temperature.