Preheat oven to 350 degrees. Grease a 9x13 baking pan very well with butter, shortening or cooking spray.
Cut the butter into pieces and place in a large bowl. Add both types of chocolate. If you are using a baking bar, chop the chocolate into pieces so it melts easier.
In 45 second increments, melt the chocolate and butter in your microwave. Stir well after each trip to the microwave. Continue this process until chocolate is smooth and glossy with no lumps.
In another large bowl, using a hand mixer, beat together the sugar, eggs and vanilla for 2 minutes until creamy. Add the chocolate mixture, and continue to beat until smooth. Add the salt and coffee granules, and slowly add the flour. Beat until flour is incorporated into the batter.
Spread batter into your greased pan. Bake for 37 minutes, until a toothpick comes out almost clean. If you want yours more done, cook for an additional minute or two. Keep in mind that once you remove the brownies from the oven, they continue to cook in the hot pan...you want these to be fudgy and moist. So don't overcook.
Let the brownies cool before cutting. Serve warm or store in an air tight container.