01 - Preheat oven to 350°F. Generously grease a 9x13 inch baking dish with melted butter.
02 - Combine chopped walnuts, pistachios, almonds, sugar, and cinnamon in a bowl. Mix thoroughly to distribute spices evenly.
03 - Unroll phyllo dough and cover immediately with a damp kitchen towel to prevent drying out during assembly.
04 - Place 8 sheets of phyllo in the prepared dish, brushing each sheet generously with melted butter before adding the next sheet.
05 - Sprinkle approximately one-third of the nut mixture evenly across the buttered phyllo surface.
06 - Layer 4 more phyllo sheets, buttering each sheet. Spread half of remaining nuts evenly over the dough.
07 - Place 4 additional phyllo sheets, buttering each one. Sprinkle the final portion of nut mixture across the surface.
08 - Finish with remaining phyllo sheets, buttering each layer thoroughly as you stack them.
09 - Using a sharp knife, carefully cut the layered pastry into diamonds or squares, cutting completely through to the bottom.
10 - Bake for 35-40 minutes until the baklava turns deep golden brown and becomes crisp throughout.
11 - While baklava bakes, combine water, sugar, lemon juice, honey, cinnamon stick, and orange peel in a saucepan. Bring to a boil, then simmer for 10 minutes until slightly thickened. Remove cinnamon stick and orange peel; allow syrup to cool slightly.
12 - Immediately upon removing baklava from oven, slowly pour the warm syrup evenly over the entire surface. Allow to cool completely for several hours to absorb syrup fully before serving.