Use an ice pick to punch out the eyes of the coconut shell. Drain out the coconut milk and strain into a measuring cup. Add enough of the milk to equal 1 cup liquid. Set aside.

Grease and lightly flour three 8 x 1-1/2 or 9 x 1-1/2-inch round baking pans. In a medium-sized bowl, stir together the flour and baking powder. In a large mixing bowl, beat the butter with an electric mixer at medium speed for about 30 seconds. Add the sugar and vanilla and beat until well combined. Add the egg yolks, one at a time, beating for 1 minute after each addition. Add the flour mixture alternately with the reserved coconut milk to the egg yolk mixture and beat at low speed until combined.

Preheat oven to 350° F. Thoroughly wash the beaters. In a medium-sized bowl, beat the egg whites at medium speed for 1 minute 30 seconds, or until stiff peaks form. Gently fold into the cake batter. Turn into the prepared pans and bake for 30 - 35 minutes, or until a tester inserted in the center comes out clean. Cool for 10 minutes on wire racks. Remove from pans and cool completely on wire racks.

Remove the coconut meat from the shell. Cut off the brown skin and discard. Shred the whole coconut and set aside.

In a small mixing bowl, whip the cream until stiff peaks form. Place one cake layer on a cake plate and spread with half the whipped cream. Add the second layer and spread with the remaining whipped cream. Add the third layer, top side up. Spread the frosting over the top and sides of the cake and sprinkle with the reserved shredded coconut. Cover and chill until ready to serve.