Cook over medium heat, stirring frequently, until thermometer registers 248 degrees, firm ball stage. Mixture should boil at a moderate, steady rate over the entire surface. Reaching firm ball stage should take 15-20 minutes.

Remove saucepan from heat; remove candy thermometer from saucepan. Immediately stir in walnuts and vanilla. Quickly pour the caramel mixture into a foiled lined and buttered 8 x 8 x 2 inch pan. When caramel is firm, use foil to lift it out of pan. Use a buttered knife to cut candy into 3/4 to 1 inch squares. Wrap each piece in clear plastic wrap. Makes about 100 (3/4 inch) pieces or about 3 pounds.