1. In a small saucepan, combine the water and sugar and bring to a boil. Once it boils, reduce the heat and simmer for 2 minutes. Add the lemon juice and orange blossom water, stir, and simmer for another 1 minute. Let it cool completely.
For the Cream:
1. In a pot, add 5 cups of milk and bring to a boil. Mix the sugar with the mastic to release its aromas. In a bowl, pour the remaining 1 cup of milk, then add the cornstarch, the sugar with mastic, and stir. Pour this mixture into the hot milk and stir until it begins to thicken. Add the heavy cream and orange blossom water. Stir for 2-3 minutes to cook the cornstarch, then pour the mahalepi into a glass dish measuring 23x32cm.
2. Let the cream cool for 4-5 minutes, then sprinkle with the coarsely ground pistachios. Place in the refrigerator to chill for 6-8 hours or overnight before serving. Cut into portions and serve with the cold syrup, allowing everyone to add as much as they desire.
