Spray a 9x13" pan with non stick cooking spray. Preheat oven to 350°.

In a small saucepan, melt the butter over medium heat. Whisk in the cocoa powder till smooth, set aside.

In a large mixing bowl, whisk together the sugar, eggs, and vanilla.

Stir in the flour, baking powder, and salt.

Add the melted chocolate mixture and stir till mixture is thoroughly combined and there are no yellow streaks. Stir in the chopped nuts.

Spread batter into prepared pan. Bake at 350 degrees for 30-35 minutes, or until middle is set. Toothpick may not come out clean, but brownies will continue to bake after you remove them from the oven.

Sprinkle the mint baking bits over the top of the brownies; let sit for 5 minutes or until melted.

With a spoon or offset spatula, spread the melted mint chocolate evenly over the brownies, making sure it goes all the way to the edges.

Let brownies sit at room temperature for 2-3 hours or until chocolate is set for easier cutting. If the chocolate sets up too hard, heat your knife by running it under hot water. (Wipe it dry before cutting the brownies.)