Preheat the oven to 350°F (175°C). Butter a 9×13 inch baking dish well.

Lay 2 sheets of phyllo in the bottom of the dish and brush generously with melted butter. Keep the remaining phyllo covered.

In a bowl, combine chopped pecans, chopped walnuts, and ground cinnamon. Mix until just combined.

Sprinkle 2–3 tablespoons of the nut mixture over the buttered phyllo.

Place 2 more sheets of phyllo on top, brush with butter, and sprinkle another 2–3 tablespoons of nuts.

Repeat these layers (phyllo, butter, nuts) until you've used all the nut mixture, butter, and phyllo, ending with about 6 layers of phyllo on top.

Using a sharp knife, cut through all the layers in a diamond shape.

Bake in the preheated oven for about 45 minutes, or until the top is golden and crisp.

While it’s baking, heat the honey in a small saucepan until just about to boil. Remove from heat and stir in the vanilla and grated lemon zest.

When the baklava comes out of the oven, pour the hot honey mixture evenly over the top.

Let it cool completely in the pan before serving.