Preparation Steps

• In a medium saucepan off heat, whisk together the whole milk, heavy cream, sugar, and salt until the sugar dissolves.
• Ladle out 0.5 cup of the cold milk mixture into a bowl and whisk in the cornstarch and flour until perfectly smooth with no lumps.
• Return the slurry to the saucepan. Set over medium heat and cook, whisking constantly, until thick, glossy, and slowly bubbling, about 5 to 7 minutes.
• Remove from heat. Stir in orange blossom water, rose water, vanilla, and mastic (if using). Taste and adjust floral notes to preference.
• For the silkiest texture, strain through a fine-mesh sieve into a shallow dish. Press plastic wrap directly onto the surface to prevent a skin from forming.
• Let cool to room temperature, then refrigerate until cold and set. Whisk briefly before serving to loosen, then top with chopped pistachios.