Step 1: Prepare the Oven and Pan

Preheat your oven to 350°F (175°C).
Line an 8×8-inch (20×20 cm) baking pan with parchment paper, leaving an overhang for easy removal.
Step 2: Make the Brownie Batter

In a medium bowl, whisk together the melted butter and sugar until smooth.
Add the eggs and vanilla extract. Mix until well combined.
Sift in the cocoa powder, flour, salt, and baking powder. Stir until just combined (do not overmix).