Here's how my birthday cake turned out:
My 50th Birthday Cake by Tracker-Backer, on Flickr
At least, that's how it looked when it went back in the refrigerator after I decorated it. The frosting did, however, feel awfully long in the piping bag. Refrigeration or no refrigeration, it's entirely possible that it slumped.
Happy Birthday! Tell us about the cake (and is there a filling?)
Well, thankfully, even though the decorating frosting felt way too long in the piping bag, it was stiff enough that it didn't slump between decorating and serving.
It is my third strawberry marble cake, a simple 9x13 sheet, served in-pan, with the ends left unfrosted (and only lightly decorated) for the benefit of my dad, who wasn't big on frosting even before he was diagnosed with mild type-2 diabetes.
Based on a standard Duncan Hines white cake mix, with 1/4 tsp of strawberry extract (McCormick) in the batter before splitting, and the contrast batter consisting of 1 cup of the main batter, 1/2 cup of seedless strawberry jam, an additional 1/4 tsp of strawberry extract, and a few drops of red food coloring (McCormick, again) in the contrast batter.
With all that jam, the batter chemistry is noticeably affected, but it does still rise.
The main frosting is your basic cold-process BC, modifying the C&H powdered sugar box recipe to replace half the butter and most of the milk with strawberry jam, the vanilla extract with strawberry extract, and a bit more red food coloring; the green decorating frosting is the main frosting with green food coloring added, and the red is with more strawberry jam and red food coloring added.
It was as successful as the first one, although not quite as successful as the second.