The Proper Crunch Foolproof Homemade English Butter Toffee

Instructions:

1. Line an 8x8 inch baking pan with parchment paper, allowing overhangs for easy removal. Lightly grease the paper.
2. In a heavy-bottomed 3-quart saucepan, combine the butter, sugar, water, corn syrup, and fine sea salt.
3. Place the pan over medium heat and stir continuously until the butter is completely melted and the sugar is fully dissolved. Ensure there is no grit on the bottom of the pan.
4. Insert a candy thermometer. Increase the heat to medium-high and bring the mixture to a vigorous boil. Stop stirring once boiling begins.
5. Continue boiling, without stirring, until the thermometer reaches exactly 300°F (149°C), the hard crack stage. This usually takes 15–20 minutes.
6. Immediately remove the pan from the heat. The mixture should be a deep amber colour. If it is too light, return briefly to low heat until the desired colour is achieved.
7. Carefully pour the hot toffee into the prepared baking pan. Do not scrape the sides of the pan.
8. While the toffee is still warm (about 10 minutes after pouring), sprinkle evenly with chopped dark chocolate or flaky sea salt, if using.
9. Allow the toffee to cool completely and harden at room temperature for at least 1 hour.
10. Lift the toffee slab out using the parchment overhang. Place it on a cutting board and shatter it into bite-sized pieces using the back of a heavy knife or rolling pin.