Roast cashews and pistachios in large skillet on medium heat 5 minutes or until fragrant, stirring frequently. Remove from skillet. Set aside.
Heat clarified butter in skillet on medium heat. Add carrots; cook and stir 5 minutes or until tender. Add milk, 1/4 cup of the sugar and 1 teaspoon of the cardamom; cook 25 minutes or until most of the milk has evaporated, stirring frequently to prevent milk from burning. Remove from heat. Cool to room temperature.
Beat egg yolks and remaining 1/2 cup sugar in medium saucepan with wire whisk 1 to 2 minutes or until pale yellow and thickened. Add cream; whisk until well blended. Stirring constantly, cook on medium heat 8 to 10 minutes or until mixture thickens and coats the back of a spoon. Remove from heat.
Pour into medium metal bowl. Stir in vanilla and remaining 2 teaspoons cardamom. Add carrot mixture and toasted nuts; mix well. Place bowl over ice water bath for 30 minutes, stirring custard occasionally.
Pour into an ice cream maker (at least 2-quart capacity). Freeze according to manufacturer's directions. Serve immediately or freeze until ready to serve. Garnish with additional cashews and pistachios, if desired.