Melt butter in heavy 3-quart saucepan. Add brown sugar and salt; stir until thoroughly combined. Stir in light corn syrup; mix well. Gradually add milk, stirring constantly. Cook and stir over medium heat until candy reaches firm ball stage (245°), about 12 to 15 minutes. Remove from heat; stir in vanilla. Pour into buttered 9 x 9 x 2-inch pan. Cool and cut into squares. Makes about 2 1/2 pounds.

Variation for Chocolate Caramels: Add 2 (1-ounce) squares of unsweetened chocolate after adding the condensed milk.