Prepare a large baking sheet with parchment paper.
Have all utensils and ingredients on hand before making the brittle.
Over medium high heat, combine the sugar, water, butter and corn syrup.
Bring to a boil and continue to stir occasionally for about 10 minutes until the caramel registers on a candy thermometer between 275° and 300°.
Do not allow the brittle to register over 300° otherwise it will surpass the hard-crack stage and will be in edible.
Working quickly from this point, remove the pot from the heat and slowly stir in the baking soda. The mixture will start to steam and bubble.
Immediately stir in the nuts and quickly scrape and spread the brittle using a silicone spatula onto the baking sheet.
It’s important to work quickly at this stage because the brittle will cool quickly.
Sprinkle the nut brittle with salt.
Allow the brittle to cook completely for at least 30 minutes before breaking it into pieces.