Heat milk in a boiling pan and let it boil. (Use full fat full cream milk). When it is about boil,simmer and let it get heated up for 5 minutes.Ensure that the milk does not overflow.
Turn off the heat and bring the milk to room temperature. You will find a thick layer of malai on top of it.
Collect the malai or cream using a clean spoon and store it in a container or glass bottle. Ensure that the container is absolutely clean and dry. Store the cream in the refrigerator. Repeat this process for 15-20 days till you have enough cream.
Once the container is full or you have enough malai to make butter, add curd to the container and allow the container to stay at room temperature for 8 hours or over night.
Transfer the contents of this container to a vessel. Add water to it and start churning using a traditional whisk (mathu) or electric beater.
The mixture will begin to froth in 2-5 minutes. Continue to whisk/beat/churn well in circular motion for few more minutes (not more than 10 minutes).
You will find a thick layer of butter gathering on the top of the froth. Collect this using your hands and transfer to a bowl with water.
Repeat the steps 6-7 till no more butter collects on top. The liquid left beneath is fresh buttermilk, which you can use in all kinds of recipes.
Gather the butter collected in the bowl together and store in a clean air tight container.
Refrigerate it and use it when needed. The butter will stay well for 1 or 2 months if stored and used right. Always use a dry spoon.