Try this Christmas cracker toffee recipe
When does a bubbling sugar mixture cross the line from smooth caramel to grainy syrup? This confection relies on precise thermal control of sucrose and butter. Boiling the butter and brown sugar together forces the water content to evaporate entirely. That process concentrates the sugars until they reach the hard-crack stage, typically between 300 degrees Fahrenheit and 310 degrees Fahrenheit. Missing this window by even a few seconds yields a chewy mass instead of a brittle sheet.
Sequencing is the primary challenge in the kitchen here. The butter and sugar mixture must be poured over the saltine base immediately after reaching temperature, or the fat will separate from the boiling syrup. Work fast. Spread the hot liquid evenly across the crackers with an offset spatula before it begins to set against the baking sheet. Sprinkle the chocolate chips over the hot surface immediately afterward. Residual heat softens the chocolate within three minutes, allowing it to spread into a uniform layer without requiring a secondary heating step.
Fresh pantry ingredients behave differently than older items. Freshly opened brown sugar retains natural moisture, which prevents crystallization during the boiling phase. Older brown sugar packed in a hardened block introduces uneven moisture levels and causes the butter to scorch before the sugar dissolves. Use newly opened packages for consistent results.
Storage requires cool conditions. Keep the finished sheet in an airtight container at room temperature for up to five days, or freeze it for up to one month between layers of parchment paper.