Preheat oven to 325 degrees F (160 degrees C). Grease and line a 9x13-inch baking pan.
Mix together All-Purpose Flour (1 1/4 cup), Unsweetened Cocoa Powder (1/4 cup), Baking Powder (1/2 teaspoon), Baking Soda (1/2 teaspoon), Powdered Confectioners Sugar (2/3 cup), Salt (1 pinch), and Vanilla Extract (2 teaspoon).
Add in Dark Chocolate (1/4 cup), Vegetable Oil (1/3 cup), and Plain Yogurt (1/2 cup). Mix to form a smooth batter.
Pour the batter into a prepared baking pan. Bake for 20 to 25 minutes or until the brownies are almost done.
Remove from the oven and immediately top with Assorted Nuts (1/4 cup), Milk Chocolate Chips (1/4 cup), and Marshmallow (1/2 cup).
Return back to the oven and bake for another 5 minutes or until the marshmallows start to melt. Let cool before cutting into bars. Enjoy!