Whisk the semolina and cornstarch into 250 ml of the cold milk in a bowl until no lumps remain. Set aside.

Pour the remaining 750 ml milk and the sugar into a 3-quart / 2.8 L heavy-bottomed saucepan. Heat over medium, whisking often, until warm and the sugar dissolves, about 4 minutes.

Whisk in the semolina slurry. Keep whisking constantly over medium heat and cook for 8 to 10 minutes, until the mixture thickens and coats the back of a spoon, with a line drawn through it holding for a second.

Remove from heat and stir in the rose water and orange blossom water.

Pour into a 9 x 13 inch / 23 x 33 cm dish or divide among 6 individual glasses. Smooth the top, cool at room temperature for 20 minutes, then cover and refrigerate at least 4 hours, until fully set and no longer liquid in the center.

Combine the sugar, water, and lemon juice in a small saucepan. Bring to a simmer over medium heat, stirring until the sugar dissolves, 3 to 4 minutes.

Simmer without stirring for 5 minutes, until slightly thickened. Remove from heat, stir in the orange blossom water, and cool completely before using, it will thicken further as it sits.

Whip the heavy cream to soft peaks. Spread or dollop it evenly over the chilled pudding.

Sprinkle the shredded coconut and chopped pistachios over the cream layer.

Drizzle each portion with 1 to 2 tablespoons of the cooled syrup just before serving, and pass extra syrup on the side.