• Preheat oven to 325°.

To prepare streusel

• Lightly spoon the flour into a dry measuring cup and level with a knife. Combine the flour and brown sugar in a small bowl. Using a pastry blender or 2 knives cut the butter into the flour mixture until it resembles a coarse meal. Stir in coconut and pecans. Set aside.

For the cake

• Coat a 12-cup Bundt cake pan with cooking spray. Sprinkle 1 tablespoon granulated sugar on the inside of bundt pan. Set aside.
• Combine cocoa powder and baking chocolate in a small bowl. Add the boiling water and stir until chocolate melts. Set aside.
• Using an electric mixer at medium speed, add the granulated sugar and butter to a large bowl and mix for 5 minutes, until well blended.
• Add the vanilla and egg whites, 1 at a time, beating well after each addition.
• Lightly spoon the flour into dry measuring cups and level with a knife. Combine the flour, baking powder, baking soda, and salt, stirring well with a whisk.
• With the electric mixer at low speed, add flour mixture to the sugar mixture alternately with the buttermilk, beginning and ending with flour mixture. Stir the melted chocolate mixture.
• Spoon half of batter into the prepared pan and top with streusel.Spoon the remaining batter over streusel and smooth the top with the back of a spoon, being sure to cover the streusel mixture.
• Bake at 325° for 1 hour or until a wooden pick inserted in center comes out clean.Cool in pan on a wire rack 10 minutes. Remove the cake from the pan and cool completely.

To prepare glaze (optional)

• Combine powdered sugar and melted butter in a small bowl. Add the milk and stir with a whisk until smooth.Drizzle glaze over top of cake.