Crush chocolate cookies in a food processor until fine crumbs form, about 1-2 minutes. Melt unsalted butter and mix it into the cookie crumbs until evenly moistened. Firmly press this mixture into a 9" springform pan and refrigerate for at least 30 minutes to set.

Melt 2 tablespoons of unsalted butter in a skillet over medium heat. Add kataifi pastry and cook, stirring occasionally, until golden and crispy, about 5-7 minutes. Mix with pistachio cream and a pinch of salt, then spread over the chilled crust.

Combine chopped semi-sweet chocolate and heavy cream in a saucepan over low heat, stirring until melted and smooth, about 3-5 minutes. Pour over the knafeh layer and chill for about 30 minutes.

In a large bowl, cream together softened cream cheese, powdered sugar, and vanilla extract until smooth, about 2-3 minutes. In a separate bowl, whip the heavy cream until stiff peaks form. Fold the whipped cream and pistachio cream into the cream cheese mixture.

Once the ganache has set, pour the pistachio cheesecake filling over the ganache and smooth the top. Cover the springform with plastic wrap and refrigerate overnight.

After chilling, carefully remove the cheesecake from the pan and transfer to a serving platter. Drizzle any remaining chocolate ganache and decorate with crushed pistachios or fresh berries. Slice and serve.