Step 1

Preheat oven to 325 degrees. Butter two 9-by-13-inch baking pans; line bottoms with parchment; butter parchment. Dust with flour; tap out excess; set pans aside. In the bowl of an electric mixer fitted with the paddle attachment, cream together butter and sugar until light and fluffy, about 3 minutes. Add vanilla and eggs, one at a time; beat until incorporated.

Step 2

Sift together flour, baking powder, and salt; add to egg mixture in three additions, alternating with the milk and beginning and ending with the flour mixture.

Step 3

Divide batter between prepared pans. Place in oven; bake until a cake tester inserted into middles comes out clean, about 30 minutes. Cool slightly on wire racks; remove from pans. Turn out cakes onto racks; cool completely.

Step 4

Spread one of the cooled cakes with the jam; place other cake on top. Using a serrated knife, trim edges of sandwiched cakes; cut into 24 two-inch squares.

Step 5

Place the coconut in a medium bowl; set aside. Place the bowl of chocolate icing over a saucepan filled with 2 inches of gently simmering water. Place a jam-filled cake squarein the bowl of chocolate icing; using forks to turn the square, coat all sides.

Step 6

Allow excess icing to drip off; transfer square to bowl of coconut (left bottom). Using clean forks to turn square, coat it with coconut. Transfer coated square to wire rack to stand until coating has set, about 15 minutes. Continue until all squares have been coated.