Preheat your oven to 350°F (175°C). Grease and flour two 9-inch round cake pans to prevent sticking.

In a large mixing bowl, sift together the flour, sugar, cocoa powder, baking powder, baking soda, and salt. This ensures an even distribution of dry ingredients.

Add the eggs, milk, vegetable oil, and vanilla extract to the dry ingredients. Beat on medium speed for 2 minutes until well combined.

Carefully stir in the boiling water. The batter will be thin, but this is normal and will create a moist cake.

Pour the batter evenly into the prepared cake pans.

Bake in the preheated oven for 30-35 minutes, or until a toothpick inserted in the center comes out clean.

Remove from the oven and let the cakes cool in the pans for 10 minutes. Then, remove from pans and transfer to a cooling rack to cool completely.

Place the chopped chocolate in a heatproof bowl.

In a small saucepan, heat the heavy cream over medium heat until it just begins to simmer. Do not boil.

Pour the hot cream over the chocolate and let it sit for 5 minutes. This allows the chocolate to melt.

Stir gently until smooth and glossy. Let it cool slightly before using.

In a large mixing bowl, beat the softened butter on medium speed until creamy.

Gradually add the sifted powdered sugar and cocoa powder, mixing on low speed until combined.

Add the heavy cream and vanilla extract. Beat on high speed for 3-5 minutes until the frosting is light and fluffy.

Once the cakes are completely cooled, place one layer on a serving plate.

Spread a layer of chocolate ganache on top of the first layer, then add a layer of chocolate buttercream frosting.

Place the second cake layer on top and repeat the process, finishing with a layer of buttercream frosting on the top and sides of the cake.

Decorate with any remaining ganache or chocolate shavings if desired.