MAKE THE SIMPLY SYRUP
While the ashta cools down, make the simple syrup. In a pot over medium heat add the water, sugar, honey, orange blossom water, and lemon juice. Bring to a boil so all the sugar is dissolved and then reduce the heat to low and simmer for 10 minutes. Transfer to a bowl and allow to cool to room temperature so it thickens up a bit more.
PREPARE THE NUT FILLING
To a food processor, add the pistachios and walnuts and pulse until crumbled. You don't want to pulse it too much to where it becomes sand-like, you still want some crunch and texture.
Transfer the nuts to a bowl and add a pinch of salt, cinnamon, and 1/4 cup of the simple syrup we made. Mix together and set aside.
MAKE THE CHEESECAKE FILLING
Using a stand mixer with a paddle attachment or handheld beater, add cream cheese and sugar to the bowl and beat on medium speed until it is creamy and smooth. Scrape down the sides of the bowl.
Then add the eggs, cornstarch, sour cream, vanilla extract, and salt and mix until creamy and smooth again. Scrape down the sides of the bowl as necessary to make sure everything is incorporated and there are no clumps.
ASSEMBLE AND BAKE
Preheat oven to 350°F.
Cut the phyllo sheets into a 9x9 square to fit the shape of the pan.
To a 9x9 pan, brush the bottom with butter. Add a layer of phyllo and brush with butter. Repeat this for a total of 10 to 12 layers. Then add some nut filling just to cover the phyllo. Pour the cheesecake filling on top and then add another layer of nuts. Add a phyllo layer on top and brush with butter. Repeat with 10 to 12 more phyllo layers and butter.
Transfer to the oven to cook for about 50 minutes or until the top is golden.
Take out of the oven and pour the simple syrup over the top and around the edges. A little goes a long way in this recipe, it doesn't need that much.
Let it cool on the counter to room temperature. Then transfer it to the fridge to chill overnight or at least 6 hours before slicing and enjoying!