01 -
Preheat oven to 350ºF.
02 -
Line an 8x8-inch pan with parchment paper.
03 -
In a large mixing bowl, melt the butter.
04 -
Add cocoa powder and vanilla extract to the melted butter and whisk until smooth.
05 -
Add brown sugar and eggs. Whisk or beat with an electric mixer until well combined.
06 -
Add flour and salt to the bowl, and beat the mixture again until smooth.
07 -
Pour the batter into the prepared pan.
08 -
Sprinkle M&Ms over the top of the batter, pressing them gently into the surface.
09 -
Bake in the oven for 40-45 minutes, or until a toothpick inserted in the center comes out clean.