Adjust your oven rack to the middle position and preheat the oven to 350 degrees F.
Line an 8.5 by 4.5-inch loaf pan with parchment paper or aluminium foil. If using foil be sure to spray with non-stick cooking spray as well to ensure the release of your brownies.
In a small bowl combine the 3 ½ ounces chocolate chips, 4 tablespoons butter, and 1 tablespoon cocoa powder and place in the microwave and by setting on 30-second intervals at a time until the chocolate chips begin to melt, then remove and stir until the mixture is smooth. Set aside and allow to cool to room temperature.
In a separate small bowl, whisk together the ½ cup plus 2 tablespoons of granulated sugar, 1 large egg, 1 large egg yolk, 1 teaspoon vanilla extract, and 1 teaspoon salt until combined.
Then whisk in the chocolate mixture until combined. Stir the ½ cup all-purpose flour in with a rubber spatula until just combined. Transfer the batter into the prepared pan and smooth the surface. Bake 15 to 20 minutes, until a cake tester comes out clean and you may need to rotate the pan halfway through baking.
Allow the brownies to cool in the pan completely before removing. Then lifting the brownies out using the paper or foil, cut the brownies into 2-inch squares.
The brownies can be stored in an airtight container or plastic bag at room temperature for up to 3 days.