Cupcake Beer?

[vegas20s]

I'm thinking you need to add some oats, flaked maze, carapils or something similar in a mini mash for body. Oats would be my choice. They would help make the beer thick. Vanilla bourbon in the secondary should help with the icing flavor. Definitely lots of crystal and maybe even some honey malt for sweetness. In my mind I'm thinking it needs to basically be a Vanilla bourbon stout BUT take out all the roasted malts and add more sweet malts.

 

[DuckiesRevenge]

I just remembered something. If you are doing vanilla beans in the secondary, first soak them in vodka...
UV makes a vodka that tastes like cake! Has a bit of the frosting flavor as well imo. Might be a good addition. I have no idea how much, maybe around a half to full cup?

 

[bovineblitz]

I'd use multiple kinds of wheat malt and a lot of crystal.

 

[JesperX]

I'd do a nice bready, sweet ESB with the Fuller's yeast and add vanilla beans after fermentation. Could toy around with spices too if that wasn't enough.