1 box light brown sugar
1 (5 oz.) can evaporated milk
1/2 stick butter, softened (4 tbsp.)
1 tsp. vinegar
1 tsp. vanilla extract
1 (12 oz.) jar chunky peanut butter (1 1/2 cups)

Butter an 8 x 8 inch baking pan. In heavy 3-quart saucepan combine brown sugar, evaporated milk, butter and vinegar. Heat to boiling over medium-low heat, stirring constantly. Set candy thermometer in place and continue cooking without stirring until temperature reaches 238 (soft ball stage). Remove from heat and beat mixture with wooden spoon until it begins to cool and thicken slightly. Stir in peanut butter and vanilla until well blended. Pour into prepared pan. Refrigerate until cooled and firm. Cut into 6 strips, then cut each strip crosswise into 6 pieces. Store in airtight container. Makes 3 dozen pieces or about 2 pounds.