Mix all ingredients in a microwave safe mug. Microwave on high 1 minute to 1 minute 15 seconds.
Cream Cheese Frosting
In a small blender or food processor, combine both ingredients until smooth and creamy. You will need to scrape the sides frequently. (Personal blenders work great for this.)
Toppings
Top carrot cake with cream cheese frosting, and garnish with additional shredded carrots and chopped pecans, if desired.