Follow these steps to create a delicious homemade baklava.

1. Step 1: Preheat the oven.

   Preheat your oven to 350°F (175°C).

2. Step 2: Prepare the nut mixture.

   In a medium bowl, combine the chopped walnuts, pistachios, sugar, and cinnamon. Mix well to combine.

3. Step 3: Layer the phyllo dough.

   Brush a 9x13 inch baking dish with melted butter. Layer 8 sheets of phyllo dough in the dish, brushing each sheet with butter before adding the next.

4. Step 4: Layer nuts and phyllo.

   Spread a thin layer of the nut mixture over the phyllo. Add two more sheets of phyllo, brushing each with butter. Repeat the layering process until all the nut mixture is used, finishing with 6-8 layers of phyllo on top.

5. Step 5: Cut the baklava.

   Using a sharp knife, cut the baklava into diamond or square shapes, cutting all the way to the bottom of the dish.

6. Step 6: Bake the baklava.

   Bake in the preheated oven for 50 minutes, or until the baklava is golden brown and crisp.

7. Step 7: Prepare the syrup.

   While the baklava is baking, combine water, honey, lemon juice, and vanilla extract in a saucepan. Bring to a boil, then reduce heat and simmer for 10 minutes.

8. Step 8: Add syrup to baklava.

   Remove the baklava from the oven and immediately pour the hot syrup over it. Let it cool completely before serving.

Ensure the syrup is hot when poured over the baklava for best absorption.