Prepare the Mixture

1. Prep the Baking Sheet: Line a baking sheet with parchment paper and set aside.
2. Combine Ingredients: In a medium saucepan, combine sugar, corn syrup, and water. Stir until the sugar is dissolved.

Cook the Mixture

1. Boil: Bring the mixture to a boil over medium-high heat without stirring. Allow it to cook until it reaches a golden amber color, about 10-15 minutes. Use a candy thermometer to check for a temperature of 300°F (150°C).
2. Add Nuts and Butter: Once the mixture reaches the desired color, carefully stir in the mixed nuts and butter. Continue to cook for an additional 2-3 minutes, stirring frequently.

Add Flavor and Cool

1. Remove from Heat: Remove the saucepan from heat and quickly stir in the vanilla extract, baking soda, and a pinch of salt. The mixture will bubble up, so be cautious.
2. Spread on Baking Sheet: Immediately pour the hot mixture onto the prepared baking sheet. Use a spatula to spread it out evenly.

Cool and Break

1. Cool Completely: Allow the brittle to cool completely at room temperature for about 20 minutes.
2. Break into Pieces: Once cool, break the brittle into pieces of your desired size.