Peel off the outer layer of the lemon grass and bruise with the back of a knife or something heavy. Cut it into three or four.
In a bowl add the yoghurt and condensed milk and give it a good mix.
Add the lemon grass and set aside to infuse for at least 6 hours. Overnight if possible.
Strain the mix, and discard the lemon grass.
Heat oven to 150 degrees
Pour the infused mix into heat proof ramekins and tap on the counter top to remove air bubbles.
Transfer the ramekins to a deep baking tray and place in the oven. Pour boiling water into the tray to create a water bath.
Bake for 25 to 30 minutes
Once cooked remove ramekins from water bath and set aside to cool. They may appear a bit wobbly but don't worry, they will set further.
Once cooled down to room temperature, immediately refrigerate.
Serve the bhapa doi as it is or garnished with slivers of pistachio