1Prepare the orange syrup by zesting and juicing oranges. Add the zest and juice to a saucepan along with water, sugar, and cinnamon sticks. Bring to a boil, reduce heat, and simmer until thickened (16-20 minutes). Strain and set aside to cool.
2In a food processor, combine chopped pecans, walnuts, cinnamon, and salt. Pulse until finely chopped.
3Melt the butter and set aside.
4Brush the bottom of a glass baking dish with melted butter. Layer 7 sheets of phyllo, brushing each sheet with butter in between.
5Spread half of the nut mixture over the phyllo.
6Top with remaining phyllo sheets, brushing each layer with melted butter.
7Score the phyllo into squares or triangles.
8Bake at 375 degrees until golden brown (about 25 minutes).
9While still hot, pour the orange syrup over the baklava.
10Let it cool completely. Dust with powdered sugar before serving.