Bring the milk to boil. Once the milk starts to rise, add some lemon juice until it starts to crack and separate. Let it cool. Pour the cracked milk into a large white or muslin cloth. Tie the cloth to the sink tap and let the water drain. I usually let it drain all night. By morning it should look like a solid lump as shown in the photograph.
To make into cubes, lightly knead the above cheese ball and roll out into a 1/4 in disc. Place a heavy weight on it to flatten for an hour or two. Cut into squares.
This can be used in various curries such as aloo mutter paneer, palak paneer, paneer tikka masala, as well as sweets such as rasagolla and rasa malai.