1 C butter
1 C light corn syrup
3 C dark brown sugar
1 C whipping cream
1 Tbls lemon juice
1 tsp salt
1 Tbls vanilla
Grease/spray a 9x9" casserole pan (or use a disposable aluminum pan - which may make it easier to remove the caramels, since you can bend the pan. If you use a disposable pan, set it on a cookie sheet for stability).
In a large 5-6 quart saucepan, combine butter, corn syrup, brown sugar, cream, lemon juice and salt. Heat over medium heat until butter is melted, then increase heat and bring mixture to a rolling boil at least 240° on a candy thermometer. If you don't get it hot enough, the caramel won't 'set'...you'll have caramel syrup (which is delicous, but not what we're really going for here!). Remove from heat and stir in vanilla (carefully...mixture will bubble up!). Immediately pour into 9x9" pan. Chill until firm enough to cut; at least a couple hours.
Remove from pan; use a large knife to cut caramels into 1" squares. Wrap each piece in wax paper: cut wax paper into 3x4" squares; roll around caramel squares and twist ends.
Store in frig; but best eaten at cool room temperature. :)