Preheat oven to 350°F (conventional, not convection). Spray a 9x13 inch pan and line one side with parchment paper, leaving an overhang on the edges for easy removal.
Melt butter in a large heatproof bowl and set aside to cool slightly while you measure the remaining ingredients.
In a separate bowl, whisk together the flour, cocoa powder, baking powder, and salt until evenly combined. Set aside.
Add the sugar to the bowl with the cooled melted butter and whisk vigorously until smooth.
Whisk in the beaten eggs and extracts, beating very well until the mixture is uniform and slightly looser than before.
Add the dry ingredient mixture to the wet ingredients and whisk until no lumps remain. If your cocoa powder is lumpy, sift it first.
Pour the batter into the prepared pan and spread evenly. Bake for 22 to 25 minutes, until the center puffs slightly and jiggles like Jello when the pan is gently shaken.
Cool completely in the pan. For clean slices, wrap the cooled pan and refrigerate for at least 2 hours, then cut with a large, sharp chef's knife.
Video
Notes
Doneness cue: The center should puff and jiggle when shaken — fully set with no movement means they have overbaked. Pull them when they still have some give and let carryover heat finish the job. Coffee extract: If you do not have coffee extract, omit it, substitute an equal amount of vanilla extract, or whisk 1 tablespoon of instant espresso powder into the dry ingredients. None of these options will make the brownies taste like coffee. Storage: Store cooled, sliced brownies wrapped in plastic wrap or in an airtight container. They will keep soft and chewy for 1 week at room temperature, up to 2 weeks in the refrigerator, or up to 2 months in the freezer. Once wrapped or sealed, the crisp edges will soften slightly.