Spinach and feta puff pastry pockets

These make a great party appetizer, a great snack, or just a great yummy thing to eat. Small number of ingredients, easy to throw together.

1 box frozen spinach, thawed, with all the water squeezed out
1 small onion, diced
1/2 cup feta
1 box puff pastry, thawed

Saute the onion in olive oil until soft, then add the spinach and cook for another minute or so. Let cool. Add the feta. Cut the puff pastry sheets into nine even squares. Place a spoonful of spinach mix in the center of each one, and wet the edges with a little water. Press the edges together to make a triangle. Bake at 400 for 15 minutes or until browned on top.