Melt the ghee in a heavy-bottomed skillet over medium heat; cook the cashews and raisins in the melted ghee until the raisins plump and the cashews are lightly browned, about 5 minutes. Remove the cashews and raisins from the pan with a slotted spoon and set aside. Add the flour to the pan and roast till brown and nutty, about 10 minutes.
Meanwhile, bring the water and sugar to a boil in a saucepan until the sugar dissolves to make a clear syrup. Stir the cardamom into the syrup; slowly pour over the roasted flour, stirring as you pour to avoid lumps. Continue cooking until the halwa pulls away from the sides of the pan, about 5 minutes more. Transfer to a serving dish and spread into an even layer; sprinkle the cashews and raisins over the halwa to serve.
