Preheat your oven to 350°F (175°C) to ensure even baking.
Line an 8x8-inch baking pan with parchment paper for easy removal.
Melt the unsalted butter in a medium saucepan over low heat and remove from heat to cool slightly.
In a large mixing bowl, combine melted butter and granulated sugar, then add vanilla extract and eggs, mixing until smooth.
In another bowl, whisk together cocoa powder, salt, baking powder, and flour. Gradually add to the wet ingredients, stirring until combined.
Fold in chocolate chips and 1 cup of M&Ms until evenly distributed.
Pour batter into prepared pan, spread evenly, and sprinkle remaining M&Ms on top. Bake for 25-30 minutes.
Let brownies cool in the pan for 10 minutes, then lift out using parchment paper and cool completely before slicing.
