Spread the frosting along the rim of a martini glass (you can also dip it into the frosting, if you prefer). Pour the sprinkles into a shallow dish or saucer, and dip the frosting-covered glass into the sprinkles. Set glass aside.

In a cocktail shaker, combine the vanilla vodka, Irish cream, milk, amaretto, powdered sugar, and ice. Close lid and shake for at least 15 seconds to mix and chill.

Pour into the prepared glass. Serve immediately.