AI have a bride that wants her buttercream cake to be sparkly. Any ideas for what I can use that will work the best?
It sounds like she might be looking for a cake with disco dust on it, which, it has been determined by veteran bakers on CC, is inedible plastic glitter bits.
To make something sparkly using edible ingredients, you could spray the buttercream with a sheen (gold or silver) and then sprinkle it with edible glitter.
AWilton makes edible glitter and there's a tutorial on cc for making your own edible glitter using edible pearl dust and gum-tex. http://cakecentral.com/b/tutorial/homemade-edible-glitter-tutorial