Place a cheesecloth on a strainer.
Heat full cream cow milk in a heavy bottom pan and stir well. When it starts to rolling boil add lemon juice or vinegar. Add 1 tablespoon at a time. Stir and add 1 tablespoon more or as require to curdle the milk completely.
You can make cottage cheese with curd in same method. First add 1/4 cup curd then add as require. It will depends on the milk. You need 1/4 to 1/2 cup curd to make cottage cheese.
When greenish whey and cottage cheese separates immediately remove from heat and pour into the strainer and wash the paneer. If you boil further after curdling your cottage cheese and rasgulla will be hard.
Wash the paneer under running water or dip the cheesecloth in a bowl filled with cold water. Wash the cottage cheese well to remove the smell of vinegar or lemon.
Squeeze the cloth well to drain all the water from cottage cheese. Remove the cottage cheese on a large dry cloth. Wrap well and put a heavy weight on it for 3-4 hours. There should be no moisture in cottage cheese. It will break in the sugar syrup if it not drained properly.
Take out the cottage cheese or paneer on a large plate.
Mash with your finger tips and heel of your palm. Mash till your palm becomes greasy and cottage cheese becomes smooth.
Make small balls. These will become double. I have made 6 rasgulla out of this cottage cheese. You can make 7 small size balls.
Flatten the balls with your palm. Place little chopped pistachio in the middle and close the edges. Make a ball again.
There shouldn’t be any crack on the balls. Press the balls between your fingers and palm tightly to make crack free balls.
In a large and broad pan heat 1 cup sugar and 4 cup water. Add saffron, cardamom powder and rose water or essence if using.
When sugar dissolved and it starts to rolling boil add the cottage cheese balls one by one. Let it boil on full flame from 2-3 minutes.
Cover and cook on medium high heat for 20 minutes.
After 20 minutes switch off the heat. Keep it covered for 3-4 hours or until completely cool down.
Serve chilled or at room temperature. You can store leftover rasgulla in refrigerator for 4-5 days.