For every Greek Grandmother, there is a different recipe, this is a basic one gleamed from averaging out several versions. I like Spanikopita (for some reason i like cooked feta dishes but dislike it rare), and it freezes nicely for quick microwave lunches.
This is written like a narrative, but the basic ingredients are 2tbs olive oil, 3-4 green onions (or 1/2 1 med. yellow onion)- diced, 1 clove crushed and diced garlic, 10oz frozen or 12 oz fresh baby spinach, salt and pepper, 8-10oz feta, 1 large egg*, pinch nutmeg. 20 or 40 sheets of filo (phylo) dough, and 1/2 cup melted butter (or 1/4 cup and a can of pam; iprefer pam).
Thaw frozen (or steam until wilted) spinach, let cool to room temperature and squeeze out extra moisture, it needs to be as dry as possible. use kitchen shears to cut into little bits (or else you will get long strings of spinach when you eat it!), set aside. heat the olive oil in a skillet till a drop of water sizzles, add diced onion and garlic (if using green onions, save the diced green part & add with spinach), saute until translucent, remove from heat. Add salt and pepper (2 pinches salt 2 grinds pepper, +/- depending on personal proclivities), add spinach and stir until well mixed; transfer to medium mixing bowl. crumble or shred feta, add to the mix, at this point it might be easier to use your hands; mix, then add the egg and nutmeg, mix until well constituted. use your hands and a spoon and create about 20 little balls from the mix, set in construction area.
Read directions for the filo dough (thaw, keep covered w/ moist tea towel, etc). if you like extra fluffy use 2 sheets, if you want them moderately fluff use 1 (i go back and forth). for each pocket, put the sheet(s) down on the counter (or large cutting board), spread butter or pam on the long middle, place a ball of goo in the lower corner (left if left handed, right if right), and fold the sheet long-wise and press around the goo, lightly spread butter or pam on sheet, and fold in triangles (like a flag) starting w/ the goo corner until it's all folded. place each on a greased/sprayed cookie sheet. when all are on the sheet, lightly brush the tops with butter. cook in 350'f oven until gold and fluffy (about 10-15 minutes, but there are a lot of variables). let sit 10 minutes to cool and serve!
note, with the filo it is okay if there are some tears, you are folding it over a bunch so it has more layers to cover the tears/holes/ etc.
OPTIONS:
reduce feta 1/2 and increase eggs to 6.
replace egg with a slurry made from 1/4 cup boiling water and 1 heaping tbs fresh ground flax seed.
use sundried tomato flavored feta.
replace 1/2 spinach w/ same volume cooked and shredded/diced chicken.
add a couple tbs minced parsley.
give the spinach a squirt of lemon juice after cooking.
replace onion with leek.
use your imagination, there's lots of options!