01 - Preheat oven to 350°F. Lightly grease a 9x13 inch baking dish with cooking spray or oil.
02 - Remove phyllo sheets from packaging and let them air-dry for 1 hour until slightly brittle. Crumple sheets into rough, loose pieces by hand.
03 - Whisk eggs and sugar in a large bowl until pale and thickened, about 3 minutes. Add yogurt, oil, vanilla, orange zest, and baking powder. Mix until smooth and fully incorporated.
04 - Gradually fold crumpled phyllo pieces into the batter, tossing gently to ensure every piece is evenly coated.
05 - Transfer mixture to the prepared baking dish. Spread evenly and smooth the top. Bake for 40 to 45 minutes until golden brown and a toothpick inserted in the center comes out clean.
06 - While pie bakes, combine water, sugar, orange juice, cinnamon stick, and orange zest in a saucepan. Bring to a boil over medium-high heat, then reduce heat and simmer for 8 minutes until slightly thickened. Remove cinnamon stick and zest; allow syrup to cool completely.
07 - Remove pie from oven. While still hot, slowly pour cooled syrup evenly over the entire surface. Let cool completely, then refrigerate for at least 2 hours to allow syrup to fully absorb before serving.