Preheat oven to 400F.

First, prepare the mixture for brushing and drizzling the phyllo dough.

1. Mix eggs and oil with yogurt. Add baking powder and then sparking water. Mix well and set aside.
2. In another bowl combine spinach, cottage cheese, sour cream, crumbled feta cheese, eggs, and salt. 
3. Carefully unroll the Phyllo sheets.
4. Reserve 6 sheets (3 for the top and 3 for the bottom). Divide the rest into 4 groups. I had 12 sheets left so I had 3 in each group.
5. Brush a baking dish with oil. If you prefer less mess, try this parchment paper.
6. Place one of the reserved sheets of phyllo on one side of the baking dish, allowing the edges to drape over the side. Place another on the opposite side. Split the third one in half and place each half on the two uncovered sides of the pan.
7. Brush with your yogurt mixture. 
8. Take one of the sheets from the first group, crumple it up a little bit, and place it on the baking dish.  Repeat with the remaining sheets from the first group. Drizzle the yogurt mixture over this again.  
9. Spread one-fourth of the spinach mixture over the first set of Phyllo.
10. Repeat the same with the remaining 3 groups of sheets.
11. Now put the 3 sheets you reserved for the top and brush each with the yogurt mixture.
12. Fold the draped edges of the bottom phyllo layers over the very top.
13. Using a sharp knife, lightly score the top Phyllo layers to create portions for serving.
14. Brush the top layer with the remaining yogurt mixture.
15. Bake in preheated oven for 35-40 minutes.
16. Allow the Spanakopita to cool slightly before cutting along the scored lines.