Heat oven to 350°F. Grease a 2.75-quart (2.6L) glass dish. (We used a roughly 9.25" x 7.5" rectangular Pyrex dish.) Set aside.
Cut hoagie rolls into 1" cubes. Place in one layer on baking sheets. Toast in oven for 5–10 minutes until lightly browned. Remove and turn off oven.
In a medium pot over medium heat, combine sugar, lemon juice, and water. Stir regularly until sugar has dissolved. Add rose water and orange blossom water. Stirring occasionally, cook until mixture thickens slightly.
Add toasted bread pieces to syrup. Mix until all pieces are coated well. Allow mixture to thicken a smidge more.
Remove from heat. Press warm, syrupy bread mixture into an even layer in the bottom of your dish.
To start the custard, mix corn starch in ½ cup of cold milk until dissolved.
In another medium pot over medium heat, combine corn starch mixture, milk, condensed milk, and cream. Stir continuously until mixture becomes smooth and thick.
Once mixture thickens, add rose water and orange blossom water. Continue stirring to allow mixture to thicken a bit more. The custard should be thick like a pudding, but still pourable.
Pour custard over bread layer. Sprinkle chopped pistachios on top.
Refrigerate dessert for 5–6 hours or overnight.
We imagine you could use most types of white bread, but we used hoagie rolls from our local farmers market.
If you don't have orange blossom water, use all rose water.