Choose a wide, heavy-bottomed pan. A stainless steel pan(10 inch or larger) works perfectly fine, but I personally prefer nonstick for kaju katli. The mixture releases more easily from the pan, and I feel there is much less sticking and wastage.
Combine the sugar and water in the pan and set it over low medium heat. Give it a gentle stir once with a rubber spatula, then let the sugar dissolve completely. The syrup may look quite thick at this point, but resist adding more water.
Keep flame on low medium and let the sugar dissolve. Once the sugar has dissolved completely and is bubbling, you are ready for the next step. We are not looking for any string consistency.
Lower the heat, if needed, and add the sifted cashew powder along with the milk powder. Mix immediately, pressing out any small lumps with the spatula as you go. At first, the mixture may look loose and slightly lumpy, but it will become smoother as it cooks.
Set a timer for 10 minutes and brace yourself for some arm work now!From this point onward, keep the heat low and stir continuously. Keep stirring and scraping continuously so the mixture cooks evenly and doesn't catch at the bottom. It is the natural tendency of cashews to stick.Keep scraping and mixing back the sides
At about 5 minute mark, you will see that the mixture is beginning to thicken and few bubbles start appearring. At this stage, the mixture has fully warmed up and raw cashews are beginning to cook. It also higher tendency to stick so continously mix.
After 6 minutes, add 1 teaspoon of ghee along with 2-3 drops of rose essence if using. The kaju katli mixture will continue to thicken for next 3-4 minutes. At this stage, the cashews sticking to the sides of the pan gets super dry so don't mix them back.
At 9 minute mark, the mixture will leave the sides of pan and start resembling a soft, sticky dough.It will begin to clump up around the spatula. If you try to bring the mixture together in one place, it will slowly spread out. It took me exactly 10 minutes to reach that stage. Be careful not to overcook it. A mixture that becomes too dry in the pan can give you crumbly katli and may crack when you try to roll it.
You can add few drops of ghee if dough is not coming together. Remove from heat. One way to check the texture of the dough is by dipping your rolling a tiny amount of dough with wet fingers. It should be soft and supple, not sticky.