2 cups sugar
2/3 cup light corn syrup
2/3 cup water
2 TBSP butter
2 cups raw Spanish peanuts (I bet you could use salted if you like your brittle a little salty)
1 TBSP soda
Combine sugar, corn syrup and water in a heavy saucepan and boil until reaches soft ball stage (yes, you need a candy thermometer)
Add butter and peanuts, boiling until the mixture is amber coloured
Add baking soda
Remove from heat and pour onto a buttered pan or platter
As soon as cool enough to handle pull out thin.
Break into pieces when cooled.