The most common theme for 30th birthday cakes is poking fun at the birthday boy or girl for getting “old!” An over the hill cake communicates to them that they are not as young as they used to be. By using black icing, you give the cake a grim and mournful appearance that says, “you are one more year closer to death.”
Another old standby is to make two cakes in the shapes of the numbers “3” and “0”. Start with a regular cake mix. Divide it into two parts, as you would when making a two-layer cake. And then carve each number out of each cake once it is cool from the oven. Frost them with festive colors and sprinkles and maybe a few candles.
Everyone has a hobby or personal interest like golf, sewing or just watching TV. Decorate your 30th Birthday cake with that theme. You can buy plastic figures playing golf and ice your cake to look like a putting green. You can make thread with a thin icing dispenser and a spool by icing a large marshmallow for the one who likes to sew. Or use the shape of a rectangular cake pan to form the screen of a TV or computer and write with icing “Warning, can cause eye strain” on the cake, with an inexpensive pair of reading glasses as a gag gift.
Perhaps a gift you would like to give the person turning 30 is a scap book of childhood pictures. You can make the cake look like the cover of a scrapbook with a photocopy picture of the person as a child in the center of the cake. Use an icing decorating dispenser to create a border around the picture. This will hold the picture on the cake, as well.
Popular today are cakes with a smooth surface. You may wonder how to create such a look with the icings that are available in your grocery store. The secret is simple: you don’t use icing, you use marshmallow cream. You can buy the cream in a jar, or with water, melt some marshmallows in the microwave until they become like icing. Put in your favorite food coloring. And this type of icing is easy to apply to a cake a create that sleek surface that an expensive cake will have. The marshmallow icing is also easy to apply different colors in a pattern like stripes or diamonds.