Line a baking sheet with parchment paper and set aside.

In a heavy-bottomed saucepan, combine the butter, sugar, water, and salt. Cook over medium heat, stirring constantly until the mixture reaches a boil.

Continue to cook without stirring until the mixture reaches 300°F (hard crack stage) on a candy thermometer.

Remove from heat and stir in the vanilla extract.

Quickly pour the toffee onto the prepared baking sheet and spread it evenly.

Sprinkle the chocolate chips over the hot toffee. Allow them to sit for a few minutes until melted, then spread the chocolate evenly over the toffee.

Sprinkle the chopped nuts over the melted chocolate and gently press them in.

Let the toffee cool completely at room temperature until hardened, about 1 hour.

Once cooled, break the toffee into pieces and store in an airtight container.