Mix chopped pistachios with sugar, cinnamon, and a pinch of salt in a bowl.
In a saucepan, combine honey, water, lemon juice, and orange blossom water. Bring to a boil, then simmer for 10 minutes. Let cool.
Brush a rectangular baking pan with melted butter.
Layer half the phyllo sheets in the pan, brushing each with butter.
Spread the pistachio filling evenly.
Layer the remaining phyllo sheets, brushing each layer with butter.
Score the top layer into diamond or square shapes using a sharp knife.
Bake at 350°F (175°C) for about 45 minutes or until golden and crisp.
While still hot, pour the cooled syrup evenly over the baklava.
Let the baklava cool and rest for at least 3 hours to absorb syrup.
Cut fully and serve.
Notes
Cover phyllo sheets with a kitchen towel while working to prevent drying out. You can substitute orange blossom water with rose water or omit entirely.