Microwave grated carrots and ghee in a large microwave-safe bowl until the ghee is melted (about two minutes).
Add milk to the bowl and microwave until the milk is steamy but not boiling, about two minutes.
Add sugar and cardamom to the bowl and microwave in two minute bursts, stirring in between each two minutes, until you can no longer see milk in the bowl. This should take about ten minutes.
Remove from heat and mix in pistachios, raisins, and saffron.
Serve the carrot halwa immediately, garnished with crushed pistachios. Optionally store in the refrigerator for up to one week and reheat before serving or even serve chilled.
Video
Notes
Cook times vary widely based on the power of your specific microwave. All times listed are just estimates. Look for my descriptions of how the dish should look at each point.