Preheat oven to 350 degrees. Butter a 9x13-inch baking dish.​ Toss together cinnamon and nuts. Unroll phyllo and cut whole stack in half to fit the dish. Cover phyllo with a damp cloth while assembling the baklava, to keep it from drying out.​ Place two sheets of phyllo in the bottom of the prepared dish. Brush generously with butter. Sprinkle 2 to 3 tablespoons of the nut mixture on top. Repeat layers until all ingredients are used, ending with about 6 sheets of phyllo. Using a sharp knife, cut baklava (all the way through to the bottom of the dish) into four long rows, then (nine times) diagonally to make 36 diamond shapes.​ Bake in preheated oven 50 minutes, until golden and crisp.​ While baklava is baking, combine sugar and water in a small saucepan over medium heat and bring to a boil. Stir in honey, vanilla and lemon zest; reduce heat and simmer 20 minutes.​ Remove the baklava from the oven and immediately spoon the syrup over it. Let cool completely before serving. Store uncovered.