Chop the bread into squares. I used 8 small bread slices.
Melt the butter in a 2 ltr pan and spread all along. Sprinkle the chopped bread into the pan.
Heat the milk till just scalding.
Break the eggs into a bowl and whisk it lightly.
Now pour the milk steadily in a stream into the bowl whilst briskly whisking the egg till the mixture turns pale yellow.
Allow to cool slightly, then whisk in the mango pulp. Add in the cinnamon. At this point, add sugar if necessary.
Pour over the bread mixture and press the bread in. Set aside for 10 minutes.
Preheat the oven to 180 degrees.
Sprinkle the pistachios on the top and bake for 25 minutes.
Serve warm as is or with a sprinkling of icing sugar.
Notes
To make an eggless version, use 2 tbsp custard powder instead of the eggs. But make sure to cook in the milk and constantly whisk in the mango pulp to have a smooth pouring sauce.