Make the Brownies:
Preheat your oven to 350°F (175°C) and grease or line an 8×8-inch baking pan with parchment paper. In a medium bowl, combine the melted butter and granulated sugar. Stir in the eggs and vanilla extract until well combined. Add the cocoa powder, flour, salt, and baking powder, mixing until smooth. If using, fold in the mini chocolate chips. Pour the brownie batter into the prepared baking pan and spread it evenly.

Bake the Brownies:
Bake for 20-25 minutes or until a toothpick inserted into the center comes out with only a few moist crumbs. Be careful not to overbake. Let the brownies cool completely in the pan.

Make the Topping:
In a small saucepan, combine the heavy cream, butter, and vanilla extract. Heat over medium-low heat until the mixture is hot and the butter is melted, but not boiling. Stir in the marshmallow fluff or mini marshmallows and continue stirring until the marshmallows are fully melted and smooth. Remove from heat and let cool slightly.

Assemble the Sno Ball Brownies:
Once the brownies have cooled, spread the marshmallow mixture evenly over the top. Then, sprinkle the shredded coconut on top, pressing gently to ensure it sticks to the marshmallow layer.

Chill and Serve:
Place the brownies in the refrigerator for about 30 minutes to allow the topping to set and firm up. Once set, slice the brownies into squares and serve.