Preheat oven to 350 degrees. Grease and flour an 8 x 8 inch pan.

In a bowl whisk together muffin mix, egg and milk.

Pour batter into prepared pan. Place chocolate candies in rows about 1/2 inch apart. Press into dough.

Bake in preheated oven for 15 - 20 minutes or until a toothpick inserted comes out with just a few crumbs.

Remove from oven and cool completely.

Make frosting by creaming together butter and powdered sugar for about 2 minutes. Beat in cocoa powder and vanilla. Beat in milk one tablespoon at a time until a stiff but spreadable mixture forms.

Spread frosting over the top. Cut into 16 squares and serve.