Pre-line a 9x13-inch baking dish with parchment paper.

In a medium saucepan, combine granulated sugar, light corn syrup, and water over medium heat. Stir until it boils (about 5 minutes).

Attach candy thermometer and continue boiling until the mixture reaches 250°F (121°C).

Stir in salted peanuts and finely diced jalapeños. Mix for 2 minutes until well combined. Raise temperature to 300°F (149°C).

Once at 300°F, remove from heat and stir in unsalted butter, baking soda, and vanilla extract.

Pour the mixture onto the prepared baking dish and spread evenly with a spatula.

Allow to cool at room temperature for 1 hour, then break into pieces.