01 -
Preheat oven to 350ºF.
02 -
Prepare an 8x8-inch pan by lining it with parchment paper.
03 -
Place butter in a small saucepan over medium-low heat. Stir with a silicone spatula often. Bubbles will begin to form and slowly get smaller. The butter will take on a darker color, and you will see small floating brown bits. This takes 10-15 minutes. Remove from heat.
04 -
Add cocoa powder and vanilla to browned butter. Whisk until smooth.
05 -
In a medium mixing bowl, beat brown sugar and eggs together until light and fluffy.
06 -
Pour butter mixture into egg mixture and beat well.
07 -
Add flour and salt. Beat until smooth.
08 -
Stir in pecans if using. Reserve some to sprinkle on top.
09 -
Transfer batter to prepared pan. Sprinkle remaining pecans on top, if using.
10 -
Bake for 40-45 minutes or until a toothpick comes out clean.