Preheat your oven to 350°F (175°C) and prepare a 9x9-inch baking pan by greasing it with butter or lining it with parchment paper.

In a medium mixing bowl, combine melted butter with granulated sugar until smooth, then add eggs and vanilla extract, mixing until fully incorporated.

Add cocoa powder, flour, baking powder, and salt to the wet mixture, mixing until smooth; fold in mini chocolate chips.

Pour the batter into the prepared pan, spreading it evenly. Bake for 20-25 minutes, checking for moisture with a toothpick.

Once baked, cool the brownies in the pan completely.

In a small saucepan, combine heavy cream, butter, and vanilla extract over medium heat, stirring until hot, then mix in marshmallow fluff.

Spread the marshmallow topping over the cooled brownies and sprinkle shredded coconut on top, pressing lightly.

Chill in the refrigerator for at least 30 minutes before slicing into squares.