Honeycomb Toffee

Honeycomb toffee, sponge toffee or cinder toffee is a sugary toffee with a light, rigid, sponge-like texture. Its main ingredients are typically brown sugar, corn syrup (or molasses or golden syrup in the Commonwealth) and baking soda, sometimes with an acid such as vinegar. The baking soda and acid react to form carbon dioxide which is trapped in the highly viscous mixture. When acid is not used, thermal decomposition of the baking soda releases carbon dioxide. The lattice structure is formed while the sugar is liquid, then the toffee sets hard.

In some regions it is often made at home, and a popular recipe for children. It is also made commercially and sold in small blocks, or covered in chocolate, popular examples being the Crunchie or Violet Crumble bar.