There is a recipe in the thread link below. Peanut brittle is easy to make. Here is a recipe from that AllenMI posted. If you like thicker brittle do not spread thinly after pouring into pans.
Yields: 2 #
2 c Sugar
1 c Light corn syrup
1 c Water
1 T Margarine or butter
2 c Peanuts
1 t Vanilla
1 t Baking soda
Generously butter 2 cookies sheets. In large heavy saucepan, combine sugar, corn syrup, and water. Cook until sugar dissolves, stirring constantly. Continue cooking until candy thermometer reaches hard crack stage (300ºF.), stirring occasionally. Remove from heat; stir in vanilla and baking soda. Pour onto cookie sheets; spread as thin as possible. Cool completely; break into pieces. Store in airtight container in cool dry place.
Here is the recipe that I have used.
2 c sugar
1 c light corn syrup
1 c water
3 c unsalted dry roasted mixed nuts
2 T butter or margarine
2 tsp vanilla
2 tsp baking soda
Mix sugar, syrup and water in a large heavy saucepan. Cover and heat to boiling. Uncover and cook rapidly to 236° on candy thermometer. (Soft ball stage) Stir in nuts slowly, keeping mixture bubbling. Cook rapidly, stirring constantly, to hard ball stage. (280°) Stir in butter continue cooking to 300°
Remove from heat. Stir in vanilla: sprinkle soda over top quickly, then stir vigorously about 15 seconds or until mixture is puffy. Pour at once into greased baking pan 15x10x1". Cool completely. Break into bite size pieces.
Store in a container that has a tight fitting lid.