1 cup chopped walnuts
1 cup butter
1 16oz package brown sugar (or 2 ¼ cups, packed)
2 cups half-and-half,or light cream
1 cup light-colored corn syrup
1 teaspoon vanilla
Line an 8×8 inch or 9×9 inch baking pan with foil, extending over the edges. Butter the foil. If desired, sprinkle walnuts over bottom of the pan. Set pan aside. In a 3 quart heavy saucepan, melt butter over low heat. Add brown sugar, half-and-half, and corn syrup; mix well. Cook and stir over medium-high heat until mixture boils.
Reduce heat to medium. Continue boiling at a moderate, steady pace, stirring frequently until the thermometer registers 248 °. (Adjust heat as necessary to maintain a steady boil) Remove saucepan from heat, remove thermometer. Stir in vanilla. Quickly pour mixture into prepared pan. When firm, use foil to lift candy out of the pan. Use a buttered knife to cut into 1 inch squares. Wrap each caramel in waxed paper or plastic wrap. Store for up to 2 weeks.
Shortcut- Prepare as above, except substitute one 14oz can of sweetened condensed milk for the half-and-half. This will take less time to reach firm-ball stage, about 15-20 minutes instead of 45-60.