Set a rack in the middle of the oven and preheat to 375 degrees F.
Lightly coat a 9 by 13-inch baking pan with non stick vegetable spray.
Put the flour, sugar, and cocoa into the bowl of a food processor fitted with the metal blade. With the machine on pulse, add the butter, bit by bit. Process until the dough is thoroughly blended and masses together.
Between 2 sheets of waxed paper or parchment, roll the dough into a 9 by 13-inch rectangle. Peel off 1 sheet of the waxed paper and fit the dough into the bottom of the prepared pan. Peel off the other sheet. With a fork, prick little holes in the dough. Refrigerate while making the macaroon.
Mix the 4 cups coconut, the egg whites, confectioners’ sugar, and coconut cream together. Lightly press this macaroon mixture over the coconut crust. Bake until golden brown and just barely set, about 15 minutes. Set on a rack to cool. Cut into bars approximately 3 by 3-inch squares. Drizzle with melted chocolate.