Grease two baking sheets. *have your butter, nuts, vanilla, baking soda, and salt in small bowls ready to add in. This is a fast moving recipe, so you'll want to be ready and set to go!* In a large pot on medium heat, stir the sugar, water, and corn syrup together. Continue to stir the mixture until your candy thermometer reads 235 degrees.
Once the mixture reaches 235 degrees, stir in the nuts.
Continue to stir until your thermometer reads 300 (softball stage). Turn off the heat and quickly add the butter, vanilla, salt, and baking soda.
Continue to stir fast until well-combined (about 30 seconds.)
***CAREFULLY*** Pour mixture onto the greased baking sheets and spread with a butter knife, or metal spoon.
Let the brittle cool completely. (We usually set it outside in the cold.)
Remove the brittle from the pan, and cack it into pieces.