With only two ingredients–which is too few, I feel.
The short version is that baking soda creates bubbles in the sugar that harden and make this… well, brittle. The kind that shatters under your teeth. Without something to aerate the sugar, it hardens stiff, and you end up with something more likely to shatter your teeth.
For a longer version read about the history of peanut brittle in our earlier post.
From the box of A.D. from Lutz, Florida, by way of Pennsylvania in the 1940s, and originating in Ohio in the 1920s.
Peanut Brittle
Heat 1/2 cup granulated sugar in an omelet pan over a low flame, stirring constantly until it is melted to a syrup.
Remove from fire, add quickly 1/4 cup chopped nuts. Pour quickly into buttered pans and let cool.