Saute the onion in a skillet until softened then add in the garlic and oregano and cook for another minute until fragrant.
Add in the spinach and cook for 3-4 minutes until all the liquid has evaporated.
Transfer to a bowl to cool.
Once cooled, add the eggs and feta cheese to the spinach mixture and stir to combine.
Spread half of the spinach mixture on each of the puff pastry sheets leaving a half an inch border.
Roll up so you have a log.
Cut each roll into 10-12 slices and place cut side down onto a lined baking sheet.
Bake at 400ºF / 200ºC for 18-20 minutes until puffed up and golden brown.
Serve warm with a green salad.