Preheat the oven to 350ºF (177ºC). Line an 8" or 9" square baking pan with foil and spray with nonstick spray. Set aside.
In a medium saucepan over medium heat, melt the butter and chopped chocolate, stirring frequently until completely smooth. Allow to cool for about 15 minutes.
Whisk sugar into cooled chocolate mixture until combined. Add the eggs one at a time, whisking after each addition until smooth. Whisk in the vanilla. Add the flour and salt and stir gently until completely combined.
Pour the batter into the prepared pan. Bake brownies for 25-30 minutes or until a toothpick inserted in the center comes out mostly clean. As brownies cool, prepare the frosting, and allow brownies to cool completely before spreading with frosting.
GERMAN CHOCOLATE FROSTING
In a medium saucepan over medium heat, combine the butter, brown sugar, egg yolk, and evaporated milk. Whisk occasionally and bring to a low boil.
Once the mixture is boiling, whisk constantly until the mixture thickens (about 5 minutes). Remove from heat, stir in the vanilla, coconut, and pecans and mix until completely combined. Frosting will thicken as it cools.
When you are ready to frost the brownies, remove the brownies by lifting the foil overhang straight up. Peel back remaining foil and place brownie block onto a large cutting board.
Spread the frosting evenly over the brownies, then cut into squares. Store leftover brownies at room temperature up to 1 week. Unfrosted brownies freeze well, up to 3 months. Thaw in refrigerator overnight, then frost.
Room temperature eggs: these incorporate into batter much more easily than cold eggs, although this is not absolutely necessary.