Preheat oven to 350 degrees F (180 degrees C). Grease and flour a 9x13 inch baking pan.
Melt the butter over medium heat. Remove from heat and stir in the chocolate until smooth. Beat in the eggs one at a time, then stir in the sugar and vanilla. Combine the flour and salt, gently stir into the mixture until just blended. Spread evenly into the prepared pan.
Bake for 25 to 30 minutes in the preheated oven, until brownies begin to pull away from the sides of the pan.
