1. Preheat oven to 350 degrees F. Then grease 13 by 9 baking pan. In heavy 3-quart sauce pan over low heat melt butter and chocolate, stirring frequently. Remove saucepan from heat. With wire whisk or spoon, beat in sugar and eggs until well blended. Stir in flour, vanilla, and salt.
2. Evenly spread batter in pan.
3. Bake 30 to 35 minutes, until toothpick inserted in center comes out clean. Cool plan on wire rack. When cool cut the brownies.