Preheat oven to 350 degrees Fahrenheit. Grease a square (9x9-inch) baking dish.

Sift the dry ingredients into a large bowl. In another large bowl whisk together the eggs and vanilla. Stir in the dry ingredients and mix together. Pour in melted butter and mix until just incorporated.

Spread half of the brownie batter onto the bottom of the prepared baking dish. Unwrap candy bars and press firmly into the batter in the pan. Top with the second half of the brownie batter and press M&M’s® halfway into the batter. (Avoid areas that already have candy bars.)

Bake at 350 degrees Fahrenheit for 25 to 30 minutes or until a toothpick comes out clean when pressed in the center of the pan. Allow brownies to cool and then cut into squares.