Prepare a baking sheet by buttering or lining with parchment paper and set aside.

Add the butter, sugar, water, and salt to a medium saucepan. Heat the pan over medium heat, stirring frequently, until the butter has melted and the sugar has dissolved.

Continue to heat over medium heat until it has reached 285 degrees F and has turned a rich caramel color. Remove from heat and stir in the vanilla.

Pour the toffee mixture onto the prepared pan and allow it to spread. Let the toffee cool for a few minutes then sprinkle the chocolate chips and let sit for about 5 minutes.

Spread the melted chocolate chips with an offset spatula and sprinkle with chopped pecans. Let the toffee cool completely, then break into pieces and enjoy.