Hello there! I need to make a dog and cat cake due tomorrow. I have everything ready to go, but my friend just called and requested "real cream frosting". 

I have looked up whipped cream fillings and they all say that it will separate in 8 hrs. I am delivering this cake tomorrow p.m. and they will have the party on Friday. I don't think it will last. 

I know the reason why they want cream is because they find BC too sweet, what can I do? This cake will be covered in fondant.

Thanks in advance for any help, tips or ideas.

if you put a pinch of salt in your BC it takes a lot of the sweet taste out
 

If you have a Gordon Food Service near you use their Bettercream. It's a stabilized whipping cream intended to use as frosting when whipped. Otherwise, use a scant teaspoon of salt for every 1 1/2 pounds of PS and some good vanilla in your icing.

How about using Ganache ? . If you are covering with fondant.  Also you are the cake decorator and know what is and isn't suitable for the timeline.  Not the customer. 

Make SMBC or IMBC. 

technically butter is just cream that has been whipped ;)