In a large bowl, mix the finely chopped walnuts, 1 cup of sugar, and ground cinnamon. Set aside.
Preheat the oven to 350°F (175°C).
Brush a 9x13 inch baking dish with some of the melted butter.
Place one sheet of phyllo dough in the baking dish and brush with melted butter. Repeat this process, layering and buttering each sheet, until you have about 8 layers of dough.
Evenly sprinkle a thin layer of the walnut mixture over the phyllo dough.
Continue layering phyllo dough, buttering each layer, and sprinkling with the walnut mixture until all the walnuts are used.
Finish with about 8 layers of phyllo dough, buttering each layer, including the top layer.
Using a sharp knife, cut the baklava into diamond or square shapes.
Bake in the preheated oven for about 50 minutes, or until the baklava is golden and crisp.
While the baklava is baking, combine the water, 1 cup of sugar, honey, vanilla extract, and lemon juice in a saucepan.
Bring to a boil, reduce heat, and let it simmer for about 10 minutes.
Remove the baklava from the oven and immediately pour the hot syrup over the top, making sure to cover all the pieces.
Allow the baklava to cool completely before serving, giving it time to absorb the syrup.
Enjoy your meal!