border

border [bohr-der] noun

A term used in many baking, cake-decorating and confectionery techniques, usually referencing the edge or edging of the item.

Bakepedia Tips

For instance, a decorative, raised border might be created for a pie using extra pie pastry. It might look like a rope or a checkerboard, or cut out leaves might be applied to create the edges. For a cake, a decorative border can be piped with various tips to create dozens of shapes, which add dimension and visual appeal. Sometimes a cake’s frosting border is used as a physical barrier, such as when it retains a fluid ganache that covers the top of the cake ( as seen in the photo above).