2 cups sugar
4 ounces (1 stick) unsalted butter
1/3 cup light corn syrup
1/2 teaspoon baking soda
1 1/2 tablespoons salt
1 1/2 cups of raw, unroasted pepitas (they toast in the syrup) or 12 ounces dry-roasted salted peanuts (do not chop)
Line a 12-by-16-by-1/2-inch sheet pan with parchment paper and spray lightly with vegetable oil.
Add the sugar, butter, corn syrup, and 1/2 cup plus 2 tablespoons water to a large saucepan (make sure this is NOT a non-stick), and stir together until all the sugar is wet. Cook over high heat until the mixture turns a medium golden (should take no less than 10 minutes).
Immediately remove from the heat, and carefully whisk in the baking soda followed by the salt (taking care, as the caramel will rise in the pan and bubble).
Switch to a wooden or metal spoon, and fold in the peanuts. Quickly pour the mixture onto the sheet pan, and spread it out over the pan using the back of the spoon before it starts to harden. (It may not cover the whole pan.)
Once the brittle is completely cool, break it into bite-size pieces with the back of a knife or other blunt object.