Color buttercream with 2 parts warm brown food color and one part ivory food color.
Using a spatula frost your cupcakes with a thin layer of frosting covering all visible cupcake.
Using a piping bag fitted with a no.12 round decorating tip, pipe a line straight down your cupcake, followed by squiggles on each side of the piped line. To create squiggles pipe back and forth in a continuous “s” shape.
Pipe another set of squiggles, continuous “s” shapes, on top of your first layer of squiggles.