Peanut Brittle

Makes 1 1/2 pounds
The key to perfect brittle is adding baking soda. It reacts with the caramelzed sugr to make the candy porous and not too hard - so it's easy to eat.
Foods with a high sugar content, such as peanut brittle, tend to draw moisture from the air, so try to make this candy when the weather is sunny and dry rather than humid or rainy.
1 tablespoon unsalted butter, plus more for pan
2 1/2 cups (12 ounces) dry-roasted, salted peanuts
1 cup sugar
1 cup light corn syrup
1 tablespoon baking soda
1. Butter a large baking pan; set aside. Combine peanuts, sugar, and corn syrup in a medium saucepan. Set over medium-high heat, and bring to a boil, stirring constantly. [If sugar starts to stick instead of melt, add a little water up to about 1/4 cup. Most recipes add water. Recipes that use roasted peanuts add them in the next step; dry-roasted are added in this step or once the mixture reaches 250°.]
2. Insert a candy thermometer. Continue boiling, without stirring, until temperature registers 295°, about 6 minutes. When sugar begins to brown, stir nuts gently to ensure even cooking. Remove saucepan from heat, and stir in the butter and baking soda; the mixture will begin to foam up, so mix quickly. Pour onto the prepared baking pan.
3. As soon as candy is cool enough to handle, use your fingers [some recipes use two forks] to stretch the brittle as thinly as possible over the baking pan. Allow the brittle to cool completely, about 45 minutes, then break into bite-size pieces. Store in an airtight container at room temperature for up to 2 weeks. Do not store in the refrigerator.