Allow butter and eggs to stand at room temperature for 30 minutes. Meanwhile, grease a 10-inch fluted tube pan. Add 1 tablespoon cocoa powder. Shake and tilt pan to coat bottom, sides, and tube; shake out any excess cocoa powder. Set pan aside. In a medium bowl stir together flour, baking soda, and salt; set aside.
In a small microwave-safe bowl microwave dark chocolate on 100 percent power (high) for 1 to 2 minutes or until melted, stirring every 30 seconds. Cool slightly. Place bourbon in a 2-cup glass measuring cup; add enough cold water to measure 1-1/4 cups liquid; set aside.
Preheat oven to 325 degrees F. Prepare Coconut Macaroon Filling; set aside. In a large mixing bowl beat butter with an electric mixer on medium to high speed for 30 seconds. Add granulated sugar and brown sugar. Beat until combined, scraping sides of bowl occasionally. Add eggs, one at a time, beating well after each addition. Beat in melted chocolate and vanilla. Alternately add flour mixture and bourbon mixture to chocolate mixture, beating on low speed after each addition just until combined. Spoon half of the batter into the prepared pan, spreading evenly. Drop Coconut Macaroon Filling by rounded teaspoons onto batter in pan, avoiding the edges. Top with the remaining batter.
Bake about 1 hour or until a wooden toothpick inserted near the center comes out clean. Cool in pan on a wire rack for 15 minutes. Remove cake from pan; cool completely on wire rack. If desired, top with No-Cook Fudge Frosting or sprinkle cake lightly with powdered sugar and additional cocoa powder.
Coconut Macaroon Filling
In a medium mixing bowl beat egg white with an electric mixer on medium speed until soft peaks form (tips curl). Gradually add sugar, beating on high speed until stiff peaks form (tips stand straight). Fold in coconut, flour, and vanilla.
No-Cook Fudge Frosting
In a large mixing bowl stir together powdered sugar and unsweetened cocoa powder. Add softened butter, boiling water, and vanilla. Beat for 1 minute with an electric mixer on medium speed. If necessary, let cool about 20 minutes or until frosting reaches spreading consistency. If frosting is too thick, beat in boiling water, 1 tablespoon at a time, until frosting reaches spreading consistency.