Trying to put the Cool whip look on top of My Ice Cream shaped cake. I have tried two so far with no success. Also anyway to make the icing stiffer...its so hot its just melting on top and my cherry is sliding....The buttercream is the stiff consistency.

Customer was on their way so I just used Fondant and sliced it on the sides with my knife. It worked for now but I'd still like to know in the future which tip to use. After thinking about it I think I worded it wrong.

I want it to look like this not the color but the texture.
 

That's a 1M tip

THANK YOU!