01 - Preheat oven to 350°F. Lightly grease a 9x13 inch baking dish with oil or butter.
02 - Remove phyllo sheets from packaging and let them dry out at room temperature for 1 hour. Crumple the dried sheets into rough, irregular pieces by hand.
03 - In a large mixing bowl, whisk together eggs and granulated sugar until pale and thickened, about 3-4 minutes. Add Greek yogurt, oil, vanilla extract, orange zest, and baking powder. Whisk until smooth and well combined.
04 - Gradually fold the crumpled phyllo pieces into the batter, using a gentle motion to ensure all phyllo is evenly coated without breaking it down too much.
05 - Pour the phyllo mixture into the prepared baking dish. Spread evenly and smooth the top. Bake for 40-45 minutes until golden brown and a wooden skewer inserted in the center comes out clean.
06 - While pie bakes, combine water, sugar, orange juice, cinnamon stick, and orange zest in a medium saucepan. Bring to a boil over high heat, then reduce heat and simmer for 8 minutes. Remove from heat and discard cinnamon stick and zest. Allow syrup to cool completely.
07 - Remove baked pie from oven. While still hot, slowly pour the cooled syrup evenly over the entire surface. Allow to cool completely, then let soak at room temperature for at least 2 hours before serving.