"Green Monster Whipped Cream Frosting" is your answer.
This frosting is made with spinach. However, your children will never taste the spinach!
Ingredients:
1 pint organic heavy whipping cream [or for a vegan version, try this]
1/4 cup sucanat
2 cups spinach
Note: Sucanat is non-refined cane sugar. Unlike refined and processed white sugar, Sucanat retains its molasses content; it is essentially pure dried sugar cane juice.
Instructions:
Puree whipping cream + spinach + sucanat just until there are no spinach pieces floating around.
Pour into a chilled metal bowl and whip the metal whisk attachment [if you have one] with your mixer.
Whip on high until stiff peaks form.
Source: http://www.edibleperspective.com/home/2010/5/6/cinco-de-delicious.html