1 c. butter
2 1/3 c. (1 lb.) brown sugar, firmly packed
1 c. light corn syrup
1 (14 oz.) can sweetened condensed milk
1/8 tsp. salt
1 tsp. vanilla
1/2 c. walnuts, chopped (optional)

In 2 quart microwave-safe pitcher, combine butter, sugar, syrup, milk and salt. Microwave on High 3 to 4 minutes, stirring once after 2 minutes. When butter is melted, stir well. Attach microwave candy thermometer. Microwave on High about 14 minutes or until mixture reaches 245 degrees. No stirring is needed. Remove from microwave; stir in vanilla and walnuts. Allow to stand 10 minutes, stirring well several times. Pour into buttered 11 x 7 inch pan. Refrigerate until cool. Invert pan. Carefully tap out whole block of candy. Cut into small squares. Wrap in wax paper. Store in refrigerator (can also freeze).