3tbspfinely chopped pecansfor the topping, plus sea salt if desired
Line a 9x9 inch baking dish with parchment paper then sprinkle the bottom evenly with chopped pecans and set aside.
Add the sugar, water, salt and butter to a heavy-bottomed pot. Place over medium heat and bring to a boil, stirring frequently.
Once boiling stir occasionally until the mixture reaches 300F, which is the hard crack stage.
Remove from heat and carefully stir in the vanilla then immediately pour over the chopped pecans. Use a spatula to spread to the edges into a flat layer then set aside to cool slightly for about 2 minutes.
Sprinkle chocolate chips over the top and cover with foil for 4 minutes so the chocolate chips soften. Use a spatula to spread the chocolate into a thin layer then sprinkle with finely chopped pecans and a bit of sea salt if desired.
Refrigerate for at least an hour before lifting from baking dish and breaking into pieces. You can score the top with a knife then snap into pieces for a cleaner look.
Toasting nuts is always a nice way to bring out more depth of flavor. Spread the chopped pecans on a baking sheet and bake at 350F for about 4 minutes or until fragrant.
You can sub in toasted chopped almonds for the pecans if desired.
A candy thermometer makes this such an easy recipe to make, do yourself a favor and pick one up if you don't have one yet.
Store toffee in an airtight container in a cool place. Humidity will make the toffee sticky while heat will melt the chocolate.
The chocolate is optional. You can leave it out or use 1/2 a cup instead for a paper thin layer. Milk, semisweet or bittersweet are all fine, it's really up to your personal preference.
I love this when topped with a sprinkle of big flaked sea salt, you can find Maldon's sea salt at most grocery stores or look for a brand that says fleur de sel.