Prepare a baking pan by lining it with parchment paper.
In a medium saucepan, melt the butter over medium heat.
Add the sugar, water, and salt to the melted butter.
Stir the mixture continuously until it comes to a boil.
Reduce the heat to low and continue stirring until the mixture reaches a golden brown color.
Remove from heat and stir in the vanilla extract.
Pour the hot toffee mixture into the prepared baking pan.
Sprinkle the chopped nuts evenly over the top of the toffee.
If using, melt the chocolate chips and drizzle over the nuts.
Let the toffee cool completely before breaking it into pieces.