8 tbsp. unsalted butter, melted, plus more for pan
1 cup flour, plus more for pan
1 tsp. baking powder
½ tsp. kosher salt
½ cup sugar
3 eggs, separated
1 tsp. vanilla extract
8 oz. milk chocolate, chopped
½ cup heavy cream
8 oz. unsweeted shredded coconut
1. Heat oven to 350°. Grease and flour an 8″ x 8″ baking pan; set aside. Whisk flour, baking powder, and salt in a bowl; set aside. In a large bowl, whisk sugar and egg whites until soft peaks form. Add butter, egg yolks, and vanilla; fold until combined. Add dry ingredients; fold until smooth. Pour into prepared baking pan; smooth top. Bake until a toothpick inserted in the middle comes out clean, about 20 minutes; cool 20 minutes. Invert cake onto a rack; cool completely. Cut into 16 squares; set aside.
2. Place chocolate in a bowl. Boil cream in a 2-qt. saucepan over high heat; pour over chocolate and let sit for 1 minute. Slowly stir until smooth; set aside. Place coconut in a pie dish. Roll cake squares in chocolate, and then roll in coconut; transfer to a rack. Chill until chocolate sets, at least 1 hour.