In a medium bowl, mix together the chopped pistachios, walnuts, and cinnamon until well combined. Preheat your oven to 350°F (175°C).

Lightly brush a 9x13 inch baking pan with olive oil. Unroll the phyllo dough and cover it with a damp cloth to prevent it from drying out.

Place two sheets of phyllo into the pan and lightly brush with olive oil. Repeat until you have about 8 sheets layered.

Sprinkle a thin, even layer of the nut mixture over the phyllo. Add two more sheets of phyllo, brush with oil, and repeat the nut and phyllo layers until all ingredients are used, finishing with 6-8 sheets of phyllo on top.

Using a sharp knife, carefully cut the baklava into diamond or square shapes all the way to the bottom of the pan. Bake for 30-35 minutes or until golden brown and crisp.

While the baklava bakes, combine honey, water, lemon juice, and lemon zest in a small saucepan. Bring to a boil, then reduce heat and simmer for 10 minutes until slightly thickened.

Remove the hot baklava from the oven and immediately pour the cooled honey syrup evenly over the top. Let it sit for at least 4 hours (or overnight) to allow the layers to absorb the syrup before serving.