Heat reduced milk in a deep non-stick pan till it comes to a boil. Keep stirring once a while.
Take chhena on a plate and rub well with your palms till it becomes smooth. Add powdered sugar, mix and rub again.
Add saffron to the milk, stir to mix and heat further. Add 1 teaspoon pistachios, stir well and switch off the heat.
Add the remaining pistachios to chhena mixture and mix well.
Discard edges of the bread and dampen them. Squeeze out the excess the water.
Place a bread slice on a worktop. Put a spoonful of chhena mixture in the centre, cover with another slice and press the edges to seal using some water. Similarly prepare the remaining.
Heat oil in a non-stick pan. Place prepared bread sandwiches on it and shallow-fry till light golden. Drain on absorbent paper.
Place the milk back on heat and put the fried bread sandwiches in it. Soak them well and bring to boil. Refrigerate till chilled.
Serve chilled garnished with saffron strands.