Preheat your oven to 200°C (392°F) and line a baking tray with parchment paper.
In a pan, heat the olive oil and sauté the onion until translucent. Add the garlic and cook briefly.
Toss in the spinach and cook until wilted. Season with salt, pepper, and a little nutmeg.
Let the spinach mixture cool slightly, then stir in the crumbled feta.
Roll out the puff pastry and spread the filling evenly across one half. Fold the other half over and press the edges together.
Brush the top with beaten egg for that beautiful golden shine.
Bake for about 20–25 minutes until puffed and golden brown.
Let it cool for a few minutes before slicing. Try not to eat it all at once!