Preheat the oven to 350°F and line an 8x8-inch baking pan with parchment paper. Set aside.
In a large mixing bowl, melt the butter and chopped chocolate in the microwave at 30-second intervals, stirring between each one, until melted and smooth.
6 tablespoons salted butter, 8 ounces bittersweet baking chocolate
Beat the sugars into the butter and chocolate mixture with a hand mixer on medium speed until fully incorporated.
½ cup granulated sugar, ¼ cup light brown sugar
Add the eggs one at a time, mixing after each addition. Then mix in the vanilla.
2 large eggs, 1 teaspoon vanilla extract
Sift the cocoa powder and cornstarch into the bowl and beat until smooth.
¼ cup unsweetened cocoa powder, 3 tablespoons cornstarch
Transfer the brownies batter to the prepared baking pan and smooth it out with a rubber spatula. Sprinkle the chocolate chips over the top of the batter.
2 tablespoons chocolate chips
Bake for 20 to 25 minutes until done. A film should form on the top of the brownies and the center shouldn’t wiggle.
Let brownies cool in the pan before enjoying.