1. Prepare the pans.
Preheat the oven to 350°F (175°C). Grease three 8-inch round cake pans. Line the bottoms with parchment circles, then lightly grease the parchment.

2. Mix the dry ingredients.
Whisk flour, cocoa powder, sugar, baking powder, baking soda, and salt in a large bowl until evenly combined.

3. Mix the wet ingredients.
In a separate bowl, whisk the eggs, whole milk, vegetable oil, and vanilla extract.

4. Make the batter.
Add the wet ingredients to the dry mixture. Mix on low speed until mostly combined. Slowly pour in the hot coffee or hot water. Mix only until smooth. The batter will be thin.

5. Divide the batter.
Divide evenly among the three prepared pans. For layers of similar thickness, weigh the filled pans or divide the batter by weight.

6. Bake.
Bake for 25–30 minutes. Begin checking at 24–25 minutes. The cakes are done when the centers spring back gently and a toothpick comes out with a few moist crumbs but no wet batter.

7. Cool completely.
Leave the cakes in their pans for about 10–15 minutes. Turn onto wire racks, remove the parchment, and cool completely before frosting.

8. Make the chocolate buttercream.
Beat softened butter for 3–4 minutes until creamy. Gradually add sifted powdered sugar and cocoa powder on low speed. Add vanilla and salt. Add heavy cream one tablespoon at a time until the frosting is smooth and spreadable. Beat for another 2–3 minutes until fluffy.

9. Level the cakes if necessary.
Once completely cool, trim noticeable domes with a long serrated knife. Do not trim unnecessarily if the layers are already flat.

10. Fill and stack.
Place the first layer on a cake board or serving plate. Spread an even layer of chocolate buttercream over it. Add the second layer and repeat. Finish with the third layer.

11. Apply the crumb coat.
Cover the top and sides with a thin layer of buttercream. Refrigerate for about 20 minutes, or until firm.

12. Apply the final buttercream coat.
Cover the chilled cake with a thicker layer of chocolate buttercream. Smooth the sides while keeping a slightly natural texture similar to the reference cake. Refrigerate for another 20–30 minutes.

13. Make the ganache.
Put the finely chopped semi-sweet chocolate in a heatproof bowl. Heat the heavy cream until steaming and just beginning to simmer around the edges. Pour it over the chocolate. Leave untouched for 2–3 minutes, then gently stir until completely smooth and glossy.

14. Test the ganache.
Allow the ganache to cool until fluid but no longer hot. Test one drip on the back of the cold cake. If it runs immediately to the bottom, wait longer. If it barely moves, warm it very gently.

15. Create the chocolate drips.
Add controlled ganache drips around the top edge. Vary their lengths naturally. Spread the remaining ganache over the top.

16. Decorate.
While the ganache is still slightly soft, arrange tall wafer bars toward the center and back. Add sandwich cookies, shorter wafer pieces, chocolate-hazelnut bites, malt balls, and assorted chocolates at different heights.

17. Finish the base.
Add a few cookies, wafer pieces, chocolate bites, malt balls, and small buttercream swirls around the bottom edge. Keep the arrangement irregular rather than perfectly symmetrical.

18. Set and serve.
Allow the decorations to set. If refrigerated, let the cake lose some of its refrigerator chill before serving for a softer cake and buttercream texture.