Prepare the phyllo pastry sheets. Remove it from the freezer and defrost it as per the instructions. It is very important to properly thaw the sheets; otherwise, it could rip very easily. I have been there and done that several times when I try to rush the thawing process.
In a small saucepan, melt the butter and add the olive oil to it. Mix both wells and keep aside.
In a large pan, heat the 2 tsp olive oil and then add the chopped spring onions. Sauté it for about 1 minute and then add the chopped spinach. Sauté until the leaves wilt and then remove it from the flame.
Transfer the spinach mixture to a large bowl and let it cool a bit.
Now add the grated/crumbled feta cheese, yogurt, salt and pepper, red chili flakes and mix well. When adding salt, remember that the feta cheese already has salt in it. So keep that in mind and add the salt accordingly.
Grease a 9 x 13 pan and start layering out the phyllo sheets. Lay one sheet and then brush with the melted butter/oil all over the surface. Lay another sheet on top and repeat the same. Do the layering, until you use up 15 sheets.
Now add the spinach mixture to the tray and spread evenly.
Top with the remaining 15 sheets of phyllo repeating the process of layering. Liberally brush the topmost layer with the remaining butter/oil mixture. Make sure to seal the edges well so the filling does not ooze out.
Bake in a preheated 375 F oven for about 45 minutes, or until the pie is golden brown. Check with a knife to see if the bottom-most layer is cooked and crunchy.
Remove from oven and let it cool for about 15 minutes.
Slice the Albanian Spinach Pie and serve.