First, preheat the oven to 350 degrees Fahrenheit (180 degrees Celsius). Then line a metal 8X8 or 9X9-inch square baking pan with parchment paper and set it aside.
Melt bittersweet chocolate and butter together in a large bowl. Heat in 30-second intervals, stirring well after each burst until smooth.
In a separate large mixing bowl, beat the granulated sugar, eggs, and vanilla together with an electric mixer on medium-high speed until pale and frothy.
Stream the melted chocolate and butter mixture into the bowl while mixing the eggs and sugar. Beat until everything is fully incorporated and smooth.
Slowly mix in the flour, cocoa powder, and salt on low speed until just combined. Be careful not to overmix.
94 grams all purpose flour, 43 grams cocoa powder, ½ teaspoon salt
Spread the brownie batter into the prepared pan. Bake for 25-35 minutes until a toothpick inserted in the center comes out with a few moist crumbs.
Carefully remove the brownies from the oven and let them cool in the hot pan for 10 minutes. Transfer the brownies to a wire rack to cool completely for 30 minutes-1 hour.
Once the brownies are cool, slice and enjoy!
Notes
Use room temperature eggs for a smooth batter that bakes evenly.Measure the flour and cocoa powder in grams with a kitchen scale for the best results.Storage: Store in an airtight container at room temperature for up to 3 days. If they are too firm, microwave for a few seconds to make them soft again.Freezing: Let the brownies cool completely, then slice and wrap each in plastic wrap. Place in a freezer bag and freeze for up to 3 months. Let thaw in the refrigerator overnight and then on the counter for 1 hour before eating.