To make the paneer: bring milk to a boil in a heavy-bottom pan. Turn the heat down, let it simmer down and bring the heat up again to boil. Add citric acid. Stir constantly. When milk curdles, remove pan from heat and leave covered for 15 minutes.
Place thin piece of muslin cloth on the bowl. Pour curdled milk into muslin and strain. Gather up the corners and tie it up to hang it to let the water drain out. Squeeze out as much water as possible. Put some heavy weight on it to drain excess liquid. Keep it overnight or as long as possible.
Place paneer on a plain surface and knead it to make it as soft and smooth as possible (approximately for 5 minutes). Add flour and continue kneading till all grains disappear.
Put sugar and water in wide mouth pan and place it on high heat. Stir till sugar melts.
Start forming little balls with the paneer. When the syrup is boiled and sugar is melted, put each ball one at a time in the syrup. Leave some space for the rossogollas to swell. They will double in size.
Keep the pan covered and on low heat for 45-50 minutes. Check the rossogolla. Taste one to make sure it is properly done. Switch off the gas. Serve it hot or at room temperature. Add a little rose essence if you like it. Garnish with almond slices.