How do you pour ganache on buttercream to create this cake?

I'm afraid the buttercream will get ruined.  Is it done last minute (please no)? Is the ganache warm?  or is something else used instead of ganache?  Thanks for any tips!!

AI believe the ganache is poured somewhat warm while its still glossy. I wouldn't wait last minute to do it I dont think you have to

I made a cake once, with the poured Ganache. I did wait until the Butter cream had crusted and the ganache was warm not hot. It worked pretty good. 

Nancy'sMom I want to marry your cake. I am in love with it. Yum

Thank you Batterupcake!!!  You made my day. :)

Thank you all.  Beautiful cake nancysmom!

Thank you Alfiesmom, And yes please post pictures. Would love to see your beautiful cake. :)