Step 1: Preheat and Prepare Pan
Preheat oven to 350°F (175°C). Line an 8×8-inch square baking pan with parchment paper, leaving overhang on two sides for easy removal. Lightly grease the parchment with butter or cooking spray. Set aside.

Step 2: Melt Butter and Mix with Sugar
In a large mixing bowl, combine melted butter and granulated sugar. Whisk together vigorously for about 30 seconds until well combined and smooth. The mixture should look glossy.

Step 3: Add Eggs and Vanilla
Add eggs and vanilla extract to the butter-sugar mixture. Whisk energetically for about 1 minute until the mixture becomes thick, smooth, and slightly lighter in color. This step incorporates air and creates that nice crackly top!

Step 4: Add Dry Ingredients
Add cocoa powder, flour, salt, and baking powder (if using) directly to the wet ingredients. Using a rubber spatula or wooden spoon, fold and stir just until no dry streaks remain. Don’t overmix! The batter should be thick, smooth, and glossy. If using chocolate chips, fold them in now, reserving a few for topping if desired.

Step 5: Pour into Pan
Pour batter into prepared pan, spreading evenly with a spatula to reach all corners. Tap the pan gently on the counter 2-3 times to release any air bubbles. If desired, sprinkle a few extra chocolate chips on top.

Step 6: Bake
Bake for 20-25 minutes. Brownies are done when the edges look set and the center has just a slight jiggle. A toothpick inserted in the center should come out with a few moist crumbs – not wet batter, but definitely not clean. Don’t overbake! For 8×8 pan, start checking at 20 minutes. For 9×9 pan (thinner brownies), check at 18 minutes.

Step 7: Cool
Remove from oven and let cool in the pan on a wire rack for at least 15-20 minutes. The brownies will continue to set as they cool. For cleanest cuts, cool completely (about 45 minutes to 1 hour) before cutting.

Step 8: Cut and Serve
Use the parchment overhang to lift brownies out of the pan. Place on cutting board and cut into 16 squares with a sharp knife, wiping blade clean between cuts. Serve and enjoy!