Step 1: In a medium saucepan, combine 1 1/2 cups sugar, water, orange juice, zest of 1 orange, and cinnamon stick (if using). Bring to a boil over medium-high heat, stirring until sugar dissolves. Reduce heat to low, simmer for 5-7 minutes until slightly thickened. Remove from heat, stir in brandy or orange blossom water (if using). Set aside to cool completely.
Step 2: Preheat oven to 350°F (175°C). Lightly grease a 9×13 inch (23×33 cm) baking dish.
Step 3: Unwrap thawed phyllo dough. Tear or cut phyllo sheets into rough 1-inch wide strips. Spread loosely in a single layer on a large baking sheet. Bake for 10-15 minutes, until lightly golden and dried out. Remove and let cool slightly.
Step 4: In a large bowl, whisk together 1 cup sugar and eggs until light and fluffy (2-3 minutes).
Step 5: Gradually whisk in olive oil, Greek yogurt, zest of 2 oranges, and baking powder until well combined.
Step 6: Gently fold in the cooled, dried phyllo strips until all phyllo is coated with the wet mixture.
Step 7: Pour the mixture into the prepared baking dish, spreading evenly.
Step 8: Bake for 40-50 minutes, or until golden brown and a skewer inserted into the center comes out clean.
Step 9: Immediately upon removing the hot cake from the oven, slowly and evenly pour the completely cold syrup all over the hot cake.
Step 10: Let the cake sit at room temperature for at least 2-3 hours (or overnight) to fully absorb the syrup and cool. Serve at room temperature, garnished as desired.