If you know someone who’d get a kick out of a birthday “sponge” cake, here are some of my secrets: Most any sort of foam rubber will do, and around boaters it’s usually easy to come by. Carve the foam to the desired cake shape, whether round, square, rectangular, or something more exotic. There are two tricks to making the Secret Sponge Cake more realistic. First, you’ll need to carve out a hole on the underside of the sponge large enough to insert a can filled with nuts and bolts, rocks, or anything heavy. Otherwise, if the recipient happens to move or pick up the cake, its light weight is a dead giveaway. I once had to talk very fast to convince a suspicious guest that the cake he’d just moved was an exquisitely fluffy old-fashioned angel food cake! Second, you need to use the point of a knife to make little slits in the sponge in which to insert each candle BEFORE icing the cake. If the candles are just stuck into the frosting, they’ll fall over — another giveaway. Using canned frosting is easiest, though any frosting will do. Keep the frosting sanitary as cruising kids love to stick their fingers in when the jig’s up. A little dab of frosting on the underside of the foam will keep the cake from sliding on the plate. Decorate in whatever fashion suits the occasion and be sure to keep the ingredients secret!