I am thinking about making "Buttercream Dream" recipe from CC recipe site. But I am wondering how many days can I leave the iced cake in the room temperature since it contains milk.
Most of the butter cream contain milk or whipped cream which I think
taste better than water.
Thanks.
My icing uses milk and I leave it out on the counter for days/weeks. Most recipes, the sugar and milk stablize each other.
Arg! 
I just threw away some cake (that I used your recipe to frost) because i was afraid the milk in the frosting, after sitting on the counter for a week, would be bad. Now I know better. NEVER THROW CAKE AWAY!
Thanks indydebi
Well, it isn't quite that simple....
As indydebi said, "most" American b/c's are shelf stable because the large amount of powdered sugar (which is hygroscopic or water absorbing) controls the water activity in the small amount of milk or other liquid.
You can't for instance, make a frosting that uses a cup of whipping cream and a cup of powdered sugar and NOT refrigerate....
HTH
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