My wife's best friend Adrienne from Canada came for a visit with her daughter Kate who is also three. They got along as well as any two toddlers will. Karen bought a cake mix and they decorated there own cakes. Of course they licked the knife and then applied the icing sampling as they went along.
Here's a picture of Heather applying frosting to her Pumpkin cake and below is a picture of Kate checking the frosting to make sure it taste just right.
And here are the end results beautifully decorated and fully vetted for great tasting frosting.