- Line the bottom of a 20-cm (8-inch) square baking pan with a strip of parchment paper, letting it hang over both sides. Butter the other two sides.
- In a saucepan, heat cream with 375 ml (1 ½ cups) of sugar, stirring until dissolved. Set aside.
- In another saucepan, bring bourbon and remaining sugar to a boil and simmer until the mixture turns golden brown, about 5 minutes. Remove from heat and gradually add cream mixture. Beware of splattering.
- Continue cooking until a candy thermometer reads 118 °C (244 °F). Remove from heat. Immediately whisk in baking soda and butter. Let cool for 30 minutes or until thermometer reads 50 °C (122 °F).
- With an electric mixer, beat until mixture thickens slightly, about 5 minutes. Stir in nuts. Spread evenly in pan. Cover with plastic wrap and let cool for 8 hours at room temperature. Remove from pan and cut into 2.5-cm (1-inch) squares. Store in an airtight container for up to 2 weeks or freeze.
Bourbon is an American whiskey, which owes its name to a county in the state of Kentucky where it was first produced.