Soak the cashews in water for 2 to 3 hours. Drain well.
Grind the soaked cashews in a high-speed blender or mixer using very little water. For 2 cups cashews, use a little less than ⅓ cup water, only as needed to help it blend into a smooth paste.
Transfer the cashew paste and sugar to a heavy-bottom pan.
Cook on low heat, stirring continuously. Add 1 tablespoon ghee and rose water, if using.
Keep cooking until the mixture thickens into a soft dough-like mass. It should leave the sides of the pan, look glossy, and feel less sticky when stirred. This usually takes about 12 to 14 minutes on low heat.
Transfer the hot mixture to a stand mixer with a flat beater and beat for about 5 minutes until smoother. If you do not have a stand mixer, let it cool just enough to handle, then knead carefully on parchment paper with greased hands.
Add 1 teaspoon ghee if needed while kneading, just enough to help bring the mixture together into a smooth, soft dough.
Place the dough between two sheets of parchment paper and roll it gently to your preferred thickness while it is still warm.
If using edible silver leaf, apply it after rolling. Let the kaju katli rest until firm, then cut into diamond shapes or squares.
Store in the refrigerator for 5 to 7 days. You can also freeze it for longer storage.