How do you make the scroll work on cakes. Do the cakes have to be fondant or can they be BC?
depeds on the kind of scrolling you want. you can use royal icing or bc, on either fondant or bc. if its fondant cut outs, you can apply that to fondant or bc.
if its painted on, or an edible writer, im not sure how well it works on bc.
I've done several BC cake with scroll work. I actually bought a set of imprinters/embossers with scroll designs (I think they are Wilton) which makes it much easier to get more a uniform design. Just wait for the BC to crust and push the imprinter into the cake, then pipe over it. You can use the same technique with fondant-just pipe over with BC or royal or make your scrolls out of fondant and attach with a little water or meringue powder mixed w/water (equal parts).