Step 1: Prepare the Syrup 

1.        In a saucepan, combine the sugar and water over medium heat.

2.        Stir until the sugar dissolves completely.

3.        Add the lemon juice and bring the mixture to a boil.

4.        Reduce the heat and let it simmer for about 10 minutes until slightly thickened.

5.        Remove from heat and add the orange blossom water if using.

6.        Set aside to cool.

Step 2: Prepare the Milk Pudding 

1.        In a separate saucepan, combine the milk, heavy cream, and sugar over medium heat.

2.        In a small bowl, dissolve the cornstarch in a bit of cold milk or water to create a slurry (a mixture).

3.        Finely crush 5 frozen mastic resins with a spoonful of white sugar in a mortar.

4.        Once the milk and cream mixture is warm, add the crushed mastic-sugar mixture and gradually add the cornstarch slurry (mixture), stirring constantly to prevent lumps.

5.        Continue to stir until the mixture thickens to a pudding-like consistency.

6.        Remove from heat and add the rose water

7.        Let the pudding come to room temperature, cover it with a plastic film, and make sure the plastic film is touching the surface of the pudding to prevent making a crust. 

Step 3: Prepare the Bread Layer 

1.        Preheat your oven to 350°F (175°C).

2.        Arrange the bread slices on a baking sheet and toast in the oven until golden brown, flipping once to ensure even toasting.

3.        Once toasted, crumble the bread slices into coarse crumbs or leave them as is.

4.        Arrange the bread on the bottom of the pan, cut, and fit until the bottom is fully covered with the toasted bread. Use preferably a transparent Pyrex, and pour the hot syrup over the bread. Let the bread soak up the syrup for 10 minutes at least before adding the pudding. 

Step 4: Assemble the dessert 

1.        Pour the hot pudding over the soaked bread crumbs in the serving dish.

2.        Spread the pudding evenly with a spatula.

Step 5: Chill and Serve

1.        Allow the dessert to cool to room temperature, then refrigerate for at least 2 hours or until fully set.

2.        Before serving, sprinkle the ground pistachios and dehydrated roses over the top for garnish.