Make Mango Curd. Put diced mango, beaten 1 egg, honey and lemon juice in a blender. Puree until smooth. Transfer to the sauce pan. Heat over medium-low heat. When it is just about to boil, reduce heat and add diced butter. Simmer until butter is melted and creamy stirring constantly. Then remove from the heat and let cool. Refrigerate until ready to use.
Preheat the oven to 350 degrees F. Butter and flour muffin baking pan.
Make chocolate cupcakes.In a bowl, combine 1 1/4 cup brownie mix, 1/4 cup all purpose flour, 1 egg, 1/2 cup milk, 2 tablespoons melted butter and 1/2 teaspoon baking powder. Mix well. Pour the batter into each muffin baking cup and bake for 20 minutes.
Spoon the mango curd into the piping bag and pipe the mango curd on each top of cupcake.