How to Make It
To make the cupcakes, preheat oven to 350°. Line a 12-cup muffin pan with paper liners.
In a large bowl, whisk together flour, baking powder, baking soda, and salt. In a medium bowl, whisk together melted butter, sugar, egg, mango puree, coconut milk, and coconut extract. Pour wet ingredients into dry, mixing just until combined.
Pour batter evenly into muffin cups, filling cups 2/3 tbsp full. Bake 20 to 22 minutes or until toothpick inserted in center of cakes comes out clean. Cool in pans 5 minutes; remove to wire racks to cool completely, about 30 minutes.
To make the frosting, beat butter and salt with an electric mixer at medium speed until creamy. Beat in coconut extract. Gradually beat in powdered sugar until smooth. Beat in cream, 1 tablespoon at a time, until frosting reaches desired spreading consistency.
Place 1/2 tbsp of frosting in a medium bowl; tint with blue food coloring and stir to swirl (do not mix completely). Spread 6 cupcakes with swirled blue frosting. Spread remaining 6 cupcakes with white frosting; sprinkle white frosted cupcakes with brown sugar. Top with candy shells, candy sharks, and paper umbrellas.