Step 1

Place 2 large pieces of parchment (at least 12" long) on a work surface. Pulse cashews in a food processor or coffee grinder to a fine powder. Set a mesh sieve over a medium bowl and sift cashew powder into bowl. Return any larger pieces still in sieve to processor and pulse again to break up further (but be careful not to turn into nut butter). Sift into bowl; set cashew powder aside.

Step 2

Heat sugar and ¼ cup water in a medium saucepan over medium, stirring constantly, until sugar is dissolved; stir in cardamom. Clip thermometer to side of pan and bring mixture to a boil (still over medium). Cook, stirring often, until thermometer registers 230°–235° (mixture should be syrupy but not thick), about 3 minutes.

Step 3

Reduce heat to low. Stir in ghee and reserved cashew powder. Cook, stirring constantly, until dough begins to pull away from sides of pan and form a mass in the center, about 3 minutes. Be careful, as the sugar will make the dough very, very hot. (You can check if the dough is ready by carefully scooping out a small spoonful and letting it cool until safe to touch. If you can roll it into a ball and it holds its shape, it’s ready.)

Step 4

Transfer dough to 1 sheet of parchment. Let cool until safe to handle (dough will stay hot in the center, so be very careful). Knead warm dough 1 minute, then top with the remaining sheet of parchment. Roll out to create an oval about ½" thick. Peel away top layer of parchment and carefully apply silver leaf (if using) to surface. Using a paring knife and a ruler, cut dough into 1"-wide strips. Then make diagonal cuts at 1" intervals across the strips to create diamond shapes. Separate out individual kaju katli. (Save scraps for snacking on later.)

Step 5

Do ahead: Kaju katli can be made 1 month ahead. Transfer to an airtight container; cover and chill, or freeze up to 3 months.