Penuche Fudge

2 cups brown sugar, firmly packed
1 cup granulated sugar
1 cup heavy cream
2 tablespoons light corn syrup
1/2 teaspoon salt
2 tablespoons butter
1 teaspoon vanilla extract
1/2 cup chopped nuts (optional)

Combine sugars, cream, syrup and salt in pan. Stir over heat to dissolve sugars. Cook to 234 degrees F on a candy thermometer. Stir occasionally. Remove from heat. Add butter without stirring. Let stand until bottom of pan is lukewarm or 120 degrees F.

Add vanilla extract and beat until creamy. Stir in nuts. Pour into a greased 9-inch square pan. Cut into squares.

Yields 36 (1 1/2-inch) pieces.