Gather all the ingredients.

In a large, heavy-bottomed saucepan, combine the butter, sugar, and salt over medium heat.

Stir constantly in one direction until the butter melts, which should take about 5 minutes.

Line a 9x13-inch baking dish with parchment paper, allowing it to overhang on two sides.

When the butter is melted, stop stirring and allow the mixture to boil. Once it reaches a boil, cook while stirring only 2 to 3 times until it turns a dark amber color and reaches 300 degrees F (150 degrees C) on a candy thermometer, which may take 20 to 30 minutes.

Quickly pour the toffee into the prepared baking dish. Sprinkle the chocolate chips on top and let them sit for 1 to 2 minutes until they soften.

Use a spatula to spread the softened chocolate evenly across the toffee.

Sprinkle the nuts over the melted chocolate and gently press down to secure them; wearing a plastic bag over your hand will help minimize mess.

Refrigerate the toffee until it sets, which should take about 1 hour. Lift it out of the baking dish using the parchment paper.

Break the toffee into pieces and store it in an airtight container.