Grease an 8-by-8-inch square pan.
Melt the butter in a saucepan over medium heat and add the dry milk powder, ground cashews, chopped cashews, 1/4 cup chopped pistachios and ground cardamom. Stir and cook until the mixture begins to turn golden, about 10 minutes.
In a separate pot, heat the sweetened condensed milk over low heat. Pour into the nut mixture and turn the heat off. Stir to combine, and then pour into the prepared pan. Sprinkle with the remaining 2 tablespoons chopped pistachios and let set for at least 20 minutes. Cut into 1 1/2-inch pieces and serve.