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.