1 Cup water
2 Cups granulated (regular) sugar
1 Cup corn syrup
2 Cups unsalted, raw Spanish peanuts (or pecans, cashews, or chopped Brazil nuts or a combination of these)
1 tsp salt
3 Tbsp butter
1/4 tsp baking soda
1 tsp Vanilla Extract
More cold butter, for greasing the candy slab
Rub cold butter all over the surface of a marble slab (or a metal jelly-roll pan, if you don’t have a marble slab).
Using a large, heavy pan, bring water to a boil on high heat. Remove pan from heat and stir in sugar until dissolved, about 2 min. Add the corn syrup and stir to combine.
Return to stove and, using a candy thermometer, heat over medium-high heat to the “hard ball” stage, or 250F.
Add the raw Spanish peanuts (or other unsalted nut combination) and salt to the molten sugar mixture; use a long-handled wooden spoon to stir occasionally. [Note: adding the nuts will drop the temperature of the boiling sugar; this is normal and the mixture will heat back up fairly quickly.] This cooks the peanuts and keeps the candy from burning on the bottom of the pan. Continue to heat mixture until temperature rises to nearly the “hard crack” stage, 295F.
Remove sugar/nut mixture from heat, and lightly stir in the butter, baking soda and vanilla to combine.
Pour molten-hot candy mixture onto the buttered slab, scraping tasty sugar bits from the bottom of the pan. (This is super hot work; you may want help – one person to hold the heavy hot pan, one person to spoon the brittle onto the cold buttered slab).
Quickly butter your hands (or don cotton or silicon gloves, or use one wooden spoon or spatula in each hand). Pull the rapidly-cooling brittle across the buttered slab, stretching it thin over the surface, as thinly as possible. Allow brittle to cool.
Break the cooled nut brittle into chunks. If you can refrain from eating it all immediately (it is that good!), store in a metal tin or sealable plastic container.