Preheat your oven to 400º. Then, melt the butter in a saucepan, taking care not to burn it.

Using a sharp knife, finely chop the pistachio nuts.

Using a sharp knife, finely chop the pistachio nuts.

Unroll your pastry, making sure the layers are lined up. Cut in half. As phyllo can dry out quickly, cover with a clean, damp cloth to keep it moist.

Using a pastry brush, brush the baking sheet with melted butter. Place 2 sheets of phyllo in the tin and brush with butter. Repeat the process until you have 10 sheets of phyllo layered. Sprinkle with the cinnamon pistachios.

Top with 2 more sheets of phyllo, brushing with butter. Sprinkle with more nuts. Repeat this process until you have used all the phyllo.

Cut the baklava all the way through, into either diamond or square pieces, about 1 by 1 1/4 inches. Note: don’t skip this step, thinking you’ll cut it when serving, as the beautiful layers of phyllo will crumble if you try to cut it after baking.

Bake for 30-35 minutes until the top is crisp and golden. Check on it toward the end, as oven times vary.

While the baklava is baking, prepare the syrup by boiling the water and sugar for about 2 minutes without stirring. Add the honey, cinnamon, and lemon zest, and simmer the mixture for about 20 minutes to allow it to thicken.

Remove the baklava from the oven and immediately pour the syrup mixture over the whole dessert until it is drenched.

It's best to let it cool before slicing and serving.