Line 9-inch square pan with aluminum foil, extending over edges. Butter bottom and sides of foil.
Combine brown sugar, butter, corn syrup and sweetened condensed milk in heavy 3-quart saucepan. Cook over medium heat 6-8 minutes, stirring occasionally, until mixture comes to a boil.
Cook 20-25 minutes, stirring occasionally, until candy thermometer reaches 240°F-242°F or small amount of mixture dropped into cold water forms soft pliable ball. Remove from heat; stir in vanilla. Pour into prepared pan. Cool 2 hours at room temperature until set.
Combine chocolate chips and whipping cream in bowl. Microwave 1-2 minutes, stirring every 15 seconds, until chocolate is melted. Spread mixture evenly over caramels. Cool 5 minutes; sprinkle with sea salt. Refrigerate until completely cooled.
Remove caramels from pan using foil; remove foil. Cut into 1-inch squares with sharp knife. Wrap caramels in candy wrappers or waxed paper. Store refrigerated. Remove from refrigerator 10 minutes before serving.
If caramels are difficult to cut after removing from refrigerator, let stand at room temperature 20-30 minutes.