• Preheat the oven to 325 degrees Fahrenheit with a rack in the lower third of the oven.
• Line an 8-inch square baking pan with parchment paper to lift out easily when brownies are cooled and spray with non-stick spray. (parchment paper should overhang a couple inches.)
• Melt the butter in a medium-sized saucepan over medium heat, whisking constantly, until it’s a pale golden brown and the particles suspended in it are reddish brown for approx 10 minutes to make browned butter.
• Remove pan from heat and then stir in the sugar.
• Add the cocoa powder, sea salt and baking powder and stir until the ingredients are thoroughly incorporated. Let the mixture cool for 5 minutes.
• Add the eggs one at a time whisking until incorporated well.
• When the mixture looks thick and shiny, add the vanilla extract and the flour.
• Stir until you no longer see streaks of flour, then beat vigorously for 50 strokes with the wooden spoon or spatula.
• At this point, the mixture should be no more than slightly warm (if not, let it cool for a few more minutes). Fold in the chocolate chunks or chips.
• Spread the batter in the lined pan, then use a knife to make light swirls in the top of the batter. Bake on the lower rack for about 25 minutes, until a toothpick inserted in the center comes out almost clean. Cool the brownies in the pan on a baking rack.
• Once the brownies are completely cool, lift the edges of the parchment paper and transfer the brownies to a cutting board.

Caramel Frosting

• In a saucepan over medium heat, melt the butter, and mix in cream and brown sugar. Boil vigorously for 1 minute.
• Remove from heat, and beat in 1/2 cup confectioners' sugar.
• Cool slightly, and beat in the vanilla and remaining 1/2 cup confectioners' sugar.
• Add more cream if the mixture is too thick.
• Pour and frost brownies fast, frosting will thicken up and be hard to spread.

Toppings

• Add some salted caramel sauce, toffee chips and mini chocolate chips.
• Use a sharp chef's knife to cut the brownies into 16 or 25 squares.