01 - Preheat the oven to 350°F. Lightly grease a 9x13 inch baking dish with butter or cooking spray.
02 - Remove phyllo sheets from packaging and let them air-dry for 1 hour until slightly crisp. 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 fully incorporated and smooth.
04 - Gradually fold the crumpled phyllo pieces into the batter, ensuring each piece is evenly coated. The mixture will appear dense and shaggy.
05 - Transfer the mixture to the prepared baking dish and spread evenly. Bake for 40-45 minutes until golden brown and a skewer inserted in the center comes out clean.
06 - While the 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. Remove from heat, discard cinnamon stick and zest, and let syrup cool completely.
07 - Remove the baked pie from the oven. While still hot, slowly pour the cooled syrup evenly over the entire surface. Allow the pie to absorb the syrup for at least 2 hours before serving.