I got a recipe for the above frosting that my son and his future bride have decided they want on their wedding cake.  It is only going to be a two tier cake, with fondant/gumpaste decorations, with cupcakes on the side.  The recipe for the frosting for the cake will be listed below, but my problem is the wedding is in June, in California, where it will be slightly warm.  It is an outdoor wedding, and I'm worried about the frosting getting too soft waiting for the wedding to be over, the meal to be eaten and the cake to be cut and served.  Is there a way to not alter the taste of this frosting, yet make it stable enough to last for several hours before being cut and served?  I think I got the recipe off of this site, but I honestly can't remember, but it was a real big hit with them and my son's future in-laws.  The place of the wedding does not have a frig large enough to accomodate food being served and the cake.

8 oz, mascarpone cheese; 8 oz. cream cheese, 1 cup butter, 2 lbs, powdered sugar, 1/2 tsp salt, 2 tsp pure vanilla.  Mix well and spread on cake.  It is a really, really good frosting.  I'm sorry, but I can't remember who posted it as I didn't write down their name, but I thank them for posting as it is a very good recipe and my family love it very much.

I used it on a cake this weekend and it was very well liked, but as it sat out on the table, it seemed to have gotten a bit softer as it sat.  I'm also concerned about fondant/gumpaste decorations on this frosting at the wedding if it starts to soften.  Will the decorations also soften and melt?  This is my first, and probably my only, wedding cake, so needless to say I am very, very nervous about it.  I am a hobby baker and only bake for family and very, very, close friends, and any assistance you can provide will be greatly appreciated.  Thank you in advance.

Um... it will melt... one thing you can try is:

4 oz mascarpone

4 oz. Cream cheese

Half cup butter

1 &1/2 cup high ratio shortening

3 lbs powdered sugar 

 salt

 Vanilla

Enough water to reach the right consistency

It won't taste exactly the same and there's still a decent chance that it will melt but that will have a much better chance at survival. Is there any way you can do a trial run? I don't mean an entire cake; just spread some icing on a plate or something and set it outside for a bit.

Another option is just explain to them that the cake they want will melt. Use good ol' reliable American bc and cover with fondant.

high humidity icings often have raw flour added -- something like a quarter cup to a regular recipe -- i use wondra flour for this -- it is a super fine flour made especially to use in gravies where it doesn't allow for lumps to form --

 you can do a search for high humidity icing -- also i would eliminate adding liquid to the icing the cream cheese and marscapone are soft enough --

 another idea is keep the cold cake in the box during the ceremony -- a compromise has to be made if it's too warm out -- less air time for the cake so it doesn't melt --

 or just fill it with the cc/marscapone icing and ice it with something sturdier --

 not to mention the safety factor of this icing not being left above 40 degrees for more than 4 hours

i did a smbc fondanted cake in June in southern California a few years ago and when i delivered it i learned the cake table was outdoors -- I just left it secure in the boxes until the last minute right after the ceremony -- it was in the 80s and the table was in the shade and all went well

 but if I used your Icing I would have left it in the boxes until the meal was over --

 best to you

Thanks for all the suggestions.  I was thinking seriously of taking an extra ice chest large enough to hold the cake, leaving it in the box inside the ice chest with some dry ice and ice.  Of course the dry ice and ice would not be touching the cake box.  I'd have the cake box well protected from the dry ice and ice.  The dry ice would keep the ice from melting so I wouldn't have the worry of water (well worth the added cost of the dry ice). The meal and cake serving would be inside a structure that is open to the outdoors (no real walls) not out in the direct sun, so if I put the cake out after the wedding service, but just before the meal, I'm thinking it might be ok.  It would give the cake enough time to thaw and not be ice cold, but also not soften so much that we'd have to worry about it, I'm hoping.  The ice chest would be protected from the sun as well during the ceremony.  We'll be at the facility decorating during the morning/early afternoon (it's an early evening ceremony) so I'll have a chance to see where the sun will be and can make sure of the placement of the ice chest then.  I have time to possibly try adding a little wondra flour to the recipe between now and then to see if it will change the flavor of the frosting, but they really have their hearts set on this particular recipe.  I'd like to not disappoint them if I don't have to, but time will tell.  The things we do for our kids!!  Right  now I'm spending a lot of my free time practicing flowers for their wedding cake -- tulips, roses, succulents -- the things we do for our kids.  Thank goodness I only have two!  But I love doing what I can for them both!  Neither of them like fondant or I'd take the easy way out, but they have requested frosting and no fondant other than the flower decorations, and after trying several different frostings/icings, the cream cheese/mascarpone cheese was the one that they liked the most, so we'll see what happens.  We've just had such crazy weather this year, I'm hoping that we aren't going to have crazy hot temps too early this year and it waits until after their wedding.  Thanks again everyone!

Not sure if this is still relevant to you but I discovered this awesome cream cheese frosting recipe recently that you can reliably use under fondant.. It makes a really super thick frosting because it calls for the liquid in the cream cheese to be strained through a cheesecloth. Because of this I had no problem getting really sharp edges under fondant and the cake itself then spent a period of time in the corner of a hot busy kitchen and didn't sag or anything...  It uses UK measures but I cannot recommend it more if this isn't an issue for you. Good luck with your project, it sounds gorgeous! :) Xx

That sounds like an interesting recipe, but they don't like fondant, so I won't be using it at all except for the flower decorations on the cake.  I was primarily concerned with the heat at this time of year in our state and whether or not the type of icing they wanted on their cake would be too soft to last in the heat.  

If you're willing to share the recipe, however, it could be used under fondant for other cakes I make.  Most people I know love the taste of cream cheese frostings more than regular buttercream frostings but I was always afraid to use it under fondant due to the softness of  cream cheese frostings.  If I had a more stable cream cheese frosting to use under fondant, I could and would do so.  So thank you for your recommendation even if it doesn't apply to my son's wedding cake, and as mentioned if you're willing to share, I would love to add it to my recipes.

Sorry! Thought I included a link but was clearly on another planet whilst writing this! Just to be clear, this is not my recipe! 

Here you go lovey :) x

http://kerrycooks.com/foolproof-thick-cream-cheese-frosting-recipe/ 

Thanks.  I'm going to give this a try.