Lucky Charms Marshmallow Brownies with Green Frosting - Zest Plate

Ingredients

• 1 box of brownie mix plus the ingredients listed on the package
• 1/3 cup marshmallow fluff
• 1 cup (2 sticks) salted butter, softened
• 1 ½ cups marshmallow fluff (about one 7 oz jar)
• 2 cups powdered sugar
• 1 tsp vanilla extract
• 1–2 tbsp heavy cream, as needed
• Green food coloring
• Lucky Charms marshmallows
• Edible gold flakes