Heat a medium saute pan over medium heat and saute the onion in a little oil until translucent add the garlic and saute for 1 minute more. Allow to cool.
In a bowl combine the onion & garlic, spinach, feta, egg, dill and season with salt & pepper.
Make a work station on a long counter or table. - First place the bowl of filling with a Tablespoon measure. - Next place a baking sheet down. On this sheet, once everything else is prepared and you are ready to fold your spanikopita, lay out the fillo and cover with a slightly damp cloth. - Next leave a 2 ft work space. Cover this space with plastic wrap for easy clean up if you wish. - Place the melted butter and a pastry brush. - Follow the space with another baking sheet. Lightly spray this one with oil.
Lay out your fillo in front of you lengthwise. Cut into 4 equal sections and place the baking sheet to your left. Cover with a slightly damp cloth.
Gently place one strip of fillo in front of you. Cover the remaining dough with the cloth. Lightly brush he strip with butter. Add another fillo strip and brush with butter. Keep repeating until you have 7 layers of fillo and butter.
Place a heaping Tablespoon of filling in the bottom right corner of the fillo strip. Lift the right corner and triangle fold it over the filling. Tuck in any filling trying to squish out. Triangle fold over to the right, tucking the filling. (This process is like folding an American flag or a paper football.) Triangle fold to the left and tuck, triangle fold to the right. You should have a triangle with no filling coming out.
Lay seam side down on the oiled baking sheet. Continue with the remaining fillo and filling until you run out of one or the other or both. (Yields 13 triangles)
Brush the tops with butter.
You can bake immediately or freeze or store in fridge for up to 12 hours.
Baking: preheat oven to 350 degrees F. Place baking sheet in center of the oven and bake 30 minutes or until golden brown.