Preheat oven to 350°F. Line a 9 x 9-inch pan with non-stick foil (or plain foil sprayed with non-stick cooking spray); set pan aside.
Chop the 6 ounces semi-sweet chocolate. Reserve about 2 ounces of the chopped chocolate for the glaze and put the remaining 4 ounces in a microwave-safe bowl for the batter.
Place 8 tablespoons of the butter (from the 11 tablespoons) with the 4 ounces reserved for the batter in the microwave-safe bowl. Microwave in 30-second intervals, stirring between intervals, until the chocolate and butter are fully melted and smooth. Let the mixture cool 5–10 minutes.
In a large bowl, whisk together 1 1/4 cups sugar, 3 eggs, 1 1/2 teaspoons vanilla, and a dash of salt until combined and slightly frothy.
Whisk the cooled chocolate-and-butter mixture into the egg mixture until evenly combined.
Stir in 1 cup flour until just incorporated and no streaks of flour remain; do not overmix.
Pour the batter into the prepared pan and smooth the top. Bake 26–28 minutes, or until a tester inserted into the center comes out with moist crumbs (not wet batter).
Remove the brownies from the oven and let them cool completely in the pan on a wire rack.
For the chocolate glaze (ganache-like): place the reserved ~2 ounces of chopped chocolate and the remaining 3 tablespoons of butter in a microwave-safe bowl. Microwave in 15–20 second intervals, stirring between intervals, until the mixture is melted and glossy. Stir until smooth.
Pour the warm glaze over the cooled brownies and use a spatula to spread it evenly to the edges.
Let the glaze set at room temperature for about 1 hour (or refrigerate 20–30 minutes to speed setting) until the topping is firm.
To serve, lift the brownies from the pan using the foil and peel the foil away. Cut into squares and enjoy.