Hang the yogurt or curd in a muslin cloth for at least an hour and then squeeze out any water whatsoever.
Take the hung curd in a mixing bowl and whisk it thoroughly. If you find it tough to whisk, use an electric hand whisk. Add the condensed milk and incorporate thoroughly.
Point to be noted here is that the amount of condensed milk required will depend on the sweetness of curd and your taste as well. If you need little more, go ahead and add it.
If you want to add any flavour at this point, like cardamom or nutmeg, or saffron infused milk, you can do it now.
Making bhapa doi in a pressure cooker
Take a tiffin box and pour the doi in the box. Close the lid and place it in the pressure cooker and add an inch level of water to the pressure cooker. Close the cooker and just give two whistles. Take it off the heat and let the steam out on its own.
When ready, take the tiffin box out and let it cool down. Keep in the refrigerator for a couple of hours for best results.
For making it in the oven or a steamer
Take small ramekins or oven proof containers and add the doi in them. Place them in a waterbath inside the oven and cover. Same with the steamer too. Cook for approximately 20 minutes at 180 degrees or till it sets.
Once done, take it out and let it cool down and refrigerate before serving.
For making in the microwave
Pour the doi in small ramekins or one large microwave safe bowl. Place the bowls in the microwave in a waterbath and microwave for a minute at full power. Let it stand for a few seconds. Open and check if it has set. Usually it sets in a minute.
The microwave time will depend on the size of your container. If you are doing one ramekin at a time, it will take about a minute and 10 seconds each time. If you are doing one large bowl, it will take about 3 minutes.