I've never heard of a raspberry cake, can you make a vanilla cake and instead of using vanilla use raspberry flavour and a bit of colouring? If you use fruit you will have to put it in the fridge. With regard to stacking, check out SPS. There is no better way for stability when stacking cakes. Leah has a tutorial on it. She converted me and many others!
2/10/14 at 2:06am