Take 250 grams of cashews and grind them into a fine powder using a mixer-grinder. Make sure not to over-grind, as it may release oil from the cashews.
In a non-stick pan, add 250 grams of sugar and 1/2 cup of water. Cook on low heat until the sugar dissolves completely and forms a syrup.
Add the cashew powder and 1/4 teaspoon of cardamom powder to the sugar syrup. Mix well and cook on low heat, stirring continuously to avoid lumps.
Cook the mixture until it thickens and starts leaving the sides of the pan. This should take about 10-12 minutes.
Grease a flat plate or tray with a little ghee. Transfer the cashew mixture onto the greased plate and let it cool for a few minutes.
Once the mixture is slightly cooled, knead it gently to form a smooth dough. If needed, add a few drops of ghee to prevent sticking.
Roll out the dough using a rolling pin to a thickness of about 5-6 mm. Let it cool completely.
Once cooled, cut the kaju katli into diamond-shaped pieces using a sharp knife. Gently remove the pieces and store them in an airtight container.