Prepare Your Workspace

1. Line the Pan: Line a baking sheet with parchment paper or a silicone mat to prevent sticking.
2. Measure Ingredients: Have all ingredients measured and ready to go—timing is crucial when making toffee.

Cook the Toffee

1. Melt Butter: In a medium saucepan, melt the butter over medium heat. Stir constantly to prevent burning.
2. Add Sugar and Salt: Gradually add the sugar and salt, stirring until fully combined.
3. Heat Mixture: Increase heat to medium-high and continue stirring until the mixture boils. Attach a candy thermometer to the pan.
4. Monitor the Temperature: Cook until the mixture reaches 300°F (hard crack stage), stirring occasionally. This takes about 10-15 minutes.
5. Add Vanilla: Remove the pan from heat and quickly stir in the vanilla extract. Be cautious, as it may bubble vigorously.

Pour and Set

1. Transfer to Pan: Pour the hot toffee onto the prepared baking sheet, spreading it evenly with a spatula.
2. Add Toppings: If desired, sprinkle chocolate chips over the hot toffee. Let them sit for a minute to melt, then spread evenly. Add nuts or sea salt on top.
3. Cool Completely: Allow the toffee to cool at room temperature until it hardens, about 10 minutes.

Break and Serve

1. Break into Pieces: Once cooled, use your hands or a knife to break the toffee into bite-sized pieces.
2. Serve or Store: Enjoy immediately or store in an airtight container.