Preheat oven to 350 degrees F (180 degrees C). Grease an 8x8-inch baking dish with butter or cooking spray.
In a large bowl, heat in the Panasonic Microwave Oven the Unsalted Butter (3/4 cup) and Unsweetened Chocolate (1/4 cup) on high in 20-second intervals, stirring in between, until melted. Stir until the chocolate is smooth.
Stir in the Granulated Sugar (2 cup) until smooth, then stir in the Vanilla Extract (1 tablespoon).
Whisk in the Egg (3). Gently stir the All-Purpose Flour (1 cup) into the mixture. Once it's almost all incorporated, stir in the Chopped Pecans (3/4 cup).
Spread the batter evenly into the baking dish, and transfer to the oven to bake for 25 minutes, or until the top is set and a toothpick inserted into the center of the pan hangs onto a few moist crumbs.
Allow the brownies to cool for 10 minutes at room temperature.
Then transfer to the refrigerator to cool for another 15 minutes.
To make the frosting, heat a small saucepan over medium heat and whisk together the Buttermilk (3 tablespoon), Unsalted Butter (4 tablespoon), and Unsweetened Cocoa Powder (4 tablespoon).
When it is just about to boil (you'll see a couple of bubbles pop to the surface), immediately pour the mixture into a large mixing bowl.
Start by adding 1/3 of the Powdered Confectioners Sugar (1 cup) into the bowl and beat with a hand mixer.
Gradually add remaining Powdered Confectioners Sugar (2 cup) one cup at a time until the frosting is smooth and fluffy. Beat in the Vanilla Extract (2 teaspoon).
Either frost the brownies in the pan or invert the pan onto a serving platter and then frost them. As soon as you've finished spreading the frosting, immediately sprinkle the Smoked Sea Salt Flakes (1 teaspoon) evenly atop the frosting.
Cut into squares. Serve. Cooking results may vary depending on microwave oven used.