After you draw the yard lines and mark the end zones, a proper football field cake needs goal posts at each end to make the field look as realistic as possible. Goal posts are basically a squared U-shape mounted on top of a vertical post. Make the posts with stick-like cookies, pretzels or bread sticks if you want an entirely edible cake, or use simple cake-pop sticks or bamboo skewers -- and eat the rest of the cake.
Edible Goal Posts
Measure the width of a sheet cake at one of the short sides. Divide this figure by 2 or 3 to find the right width for the goal posts. Each finished goal post should be one-third to one-half the total width of the end zone. For example, the goal posts for a 9-by-13-inch cake should be 3 to 4 inches wide.
Cut three pieces of rolled wafer cookies, such as Pirouline, pretzel rods, bread sticks or similar rigid, stick-like food to the measurement needed for the goal post width. Cut a fourth piece to the same length, but add the cake height to the final measurement -- this is the vertical post that supports the U-shaped goal. If the cake is 2 inches tall and the desired goal post width is 4 inches, cut this fourth piece to 6 inches long.
Fill a plastic bag with royal icing and snip one corner of the bag. Royal icing, and icing made from meringue powder, powdered sugar and water, binds like glue and dries hard.
Arrange the pieces on wax paper, with the three shorter pieces in a U-shape and the longer piece placed vertically at the center of the horizontal piece in the U-shape. Squeeze royal icing onto the parts of the goal post where the pieces connect. Push the pieces together firmly to "glue" them together. Repeat for the other goal post. Allow the royal icing to dry and harden overnight before moving the goal posts.
Thin royal icing with water to a drizzling consistency -- it should be able to coat a spoon but drizzle off easily. Add food coloring gel in your choice of color, if desired. Hold each goal post upside down by the vertical post. Dip the goal post into the royal icing -- you only need to dip it down to the point along the vertical post that will be concealed in the cake. You can also use a spoon to drizzle it over the goal posts until you achieve full coverage. Hold the goal post upside down over wax paper to allow the excess coating to drip off. Tie a piece of string around the uncoated ends and hang the posts upside down for about 1 hour or until the coating hardens -- this eliminates the flatness that can occur on one side of the goal post when you lay it flat.
Push each goal post down into the cake, centered at each end of the cake.
Inedible Goal Posts
Measure the width of the sheet cake. Divide by 2 or 3 to find the figure for a goal post that measures one-third to one-half the width of the cake. Measure the height of the cake.
Cut three uniform pieces of cake pop sticks, straws, bamboo skewers or similarly shaped clean objects to the length equal to one-third to one-half the cake width. Cut a fourth piece to this length, plus the height of the cake.
Lay the four pieces out on a flat work surface to form the goal post shape. Glue the pieces together with hot glue or tacky glue. Let them set until the glue dries completely. Do not use hot glue with plastic straws because the heat can melt the plastic.
Stand the goal posts upright at the center of each end zone, positioned as close to the cake ends as possible.
Cookies, pretzels and bread sticks are likely to crumble or crush as you try to cut them. You may go through several of each before you get four pieces with clean cut ends.
The royal icing coating dries hard, but the goal posts are still completely edible. You can try coating them with melted chocolate or melting candy, but the heat can soften the royal icing that binds the posts together.