1In a 3-quart casserole blend together brown sugar, milk, butter, corn syrup and salt. Microwave uncovered 5 minutes on high, until sugar is dissolved, stirring after 2 1/2 minutes. Remove form oven and stir thoroughly to blend. Microwave 6 minutes longer on high, stirring after 3 minutes.
2Test by dropping a small amount into very cold water to form soft ball (240F). Let mixture cool to lukewarm, spoon until it begins to thicken. Add vanilla and nuts and continue beating until mixture is very thick. Spread evenly in buttered 8x8 pan. Refrigerate until firm, then cut into squares.