Prepare the nut filling: Add the toasted walnuts, toasted pistachios, cinnamon, and salt to a food processor. Pulse until coarsely ground, you want small pieces, not a fine powder. Transfer to a bowl and set aside.
Make the syrup: In a small saucepan, combine the water, sugar, honey, lemon juice, and rose water (if using). Bring to a boil over medium heat, stirring until the sugar has completely dissolved. Reduce to a gentle simmer and cook for 4–5 minutes.
Pour about ⅓ of the syrup over the nut mixture and stir until evenly coated. Reserve the remaining syrup for later and let it cool completely.
Prepare the pan: Preheat the oven to 170°C (340°F). Grease the bottom and sides of a 9-inch (23 cm) springform pan with butter.
Make the cheesecake filling: In a large bowl, beat the cream cheese and sugar until completely smooth and creamy.
Add the eggs one at a time, mixing well after each addition. Add the sour cream (or yogurt), heavy cream, vanilla extract, lemon zest, and cornstarch. Mix just until smooth and fully combined. Avoid overmixing.
Assemble the cheesecake: Keep the phyllo dough covered with a slightly damp towel while working to prevent it from drying out.
Place one sheet of phyllo into the prepared pan, pressing it gently into the bottom and sides while allowing the excess to hang over the edges. Lightly brush with melted butter.
Repeat with 8–10 sheets, rotating them slightly each time so the entire pan is evenly covered.
Spread half of the nut mixture evenly over the phyllo crust. Pour the cheesecake filling over the nuts and smooth the top. Sprinkle the remaining nut mixture evenly over the cheesecake filling.
Cover with 2–3 more buttered phyllo sheets, then gently fold the overhanging phyllo over the top to enclose the cheesecake. Brush the top generously with the remaining melted butter.
Bake: Bake for 45–50 minutes, or until the phyllo is deep golden brown and the cheesecake is mostly set with a slight wobble in the center.
If the top begins browning too quickly, loosely tent it with aluminum foil after about 30 minutes.
Finish and chill: While the cheesecake is still warm, slowly pour the remaining cooled syrup evenly over the top, allowing it to soak into the phyllo.
Let the cheesecake cool completely at room temperature, then refrigerate for at least 4 hours, preferably overnight.
Before serving, garnish with chopped pistachios.
Video
Notes
Rose Water: Rose water (also called rose essence or rose floral water) is a fragrant ingredient commonly used in Middle Eastern desserts like baklava. It's optional, but I highly recommend adding it, it gives the syrup the classic floral aroma that makes baklava so special. A little goes a long way, so don't be tempted to add too much.
How do I know when the cheesecake is done? Since the cheesecake is covered with phyllo, you won't be able to see the center. Instead, gently shake the pan, it should have a slight wobble in the middle but shouldn't look liquid underneath the phyllo. The cheesecake will continue to set as it cools.
Working with phyllo dough: Phyllo dries out very quickly. Keep the unused sheets covered with a slightly damp kitchen towel while you work, and don't worry if a sheet tears a little, once layered and brushed with butter, no one will notice.
Make ahead: This cheesecake is even better the next day. An overnight chill allows the flavors to develop and makes the slices much cleaner.
Storage: Store covered in the refrigerator for up to 4 days. The phyllo will gradually soften over time but will still taste delicious.