3 cup whipping cream
2 cup sugar
1½ cup white Karo syrup
1 tsp. vanilla
Dissolve sugar in Karo. Add 1 cup of cream and cook to soft ball stage. Add 2nd cup of cream and cook to soft ball stage. Add 3rd cup of cream and cook to soft ball stage. Add vanilla and nuts if desired. Pour immediately into buttered dish. Do not scrape pan or small hardened flecks will end up in your caramels.
Soft ball stage is about 235° F at sea level. Above 4,500 ft., need to subtract 4-5° F, for 231-235° F. Optimal seems to be 234° F
2024 Update: Worked best when melted the sugar and corn syrup first, added each cup of cream with minimal stirring, cooking on medium until the digital thermometer read 234° F. Had to take it off the heat for the final at 231° F because it was starting to form crystals. Add vanilla and do not scrape the bottom!