Preheat your oven to 350°F (175°C). Grease and flour three 9-inch round cake pans to ensure easy removal.

In a small bowl, combine the finely chopped semi-sweet chocolate, Dutch-process cocoa powder, and boiling water. Stir until smooth and let it cool slightly.

In another bowl, whisk together the all-purpose flour, baking soda, and salt to evenly distribute the leavening agent.

In a large mixing bowl, cream the softened butter with granulated sugar and brown sugar until the mixture is light and fluffy, about 3 to 5 minutes.

Beat in the eggs, one at a time, mixing well after each addition, then stir in the vanilla extract.

Gradually add the flour mixture and sour cream in alternate batches, starting and ending with flour. Mix until just combined.

Fold in the melted chocolate mixture until everything is evenly incorporated.

Divide the batter evenly among the prepared cake pans. Bake in the preheated oven for 25 to 30 minutes, or until a toothpick inserted into the center of the cakes comes out clean. Allow the cakes to cool in the pans for 10 minutes before transferring to wire racks.

For the frosting, combine the heavy cream, granulated sugar, egg yolks, and salt in a saucepan over medium heat. Stir continuously until the mixture thickens slightly.

Remove the saucepan from the heat and stir in the butter, vanilla extract, toasted pecans, and shredded coconut. Allow the frosting to cool to room temperature.

Once the cakes are completely cool, layer them with frosting, covering the top and sides of the cake. Slice and serve to enjoy this tempting treat.