Chocolate cake

1. Preheat oven to 325F (no fan) and prepare 3 9" pans with parchment paper and butter
2. In a bowl, combine the flour, baking powder, baking soda, granulated sugar, light brown sugar and salt. Whisk together until no lumps remain
3. In a separate bowl, whisk together the eggs, vegetable oil, buttermilk and sour cream until smooth
4. Add the dry ingredients to the wet in 2 additions, and gently whisk and fold until they are just combined and no big lumps remain. Do not overmix
5. In a separate small bowl, add the cocoa powder and instant coffee. Pour over the boiling water and whisk until a smooth shiny mixture forms
6. Pour the cocoa mixture onto the remaining batter, and gently fold until a chocolate cake batter forms
7. Divide the batter evenly between the 3 prepared cake pans
8. Bake for ~18-20 minutes until a toothpick inserted in the center comes out with light moist crumbs attached
9. Let the cakes cool in the pans for 20 minutes, then carefully remove them and place on a wire rack. Let cool completely (I recommend refrigerating for 1 hour)

Chocolate pudding

1. Add all ingredients for the pudding to a large nonstick saucepan
2. Place on the stove on low heat, and use a whisk to gently stir and cook the pudding until the butter and chocolate melt and all ingredients combine. It will look strange and lumpy in the beginning but will come together as it cooks 
3. Keep cooking and stirring on low heat until the pudding comes to a boil. After this point, it will start to thicken up quickly. Keep an eye on it, and cook until the pudding feels reaches a thick, custard like consistency and starts to hold shape (if you run a spoon through it, it should leave a mark that doesn't dissolve). Remove from the heat. The total cooking time should be around 10 minutes
4. Strain the pudding to remove any lumps. Pour it into a wide plate, cover with cling wrap, and refrigerate for at least an hour until cool and thick

Chocolate fudge frosting

1. Add the chocolate and cream to a microwave safe bowl. Microwave in 20 second increments, stirring in between, until the chocolate has melted and a smooth ganache forms. Set it aside
2. Add the cream cheese and sugar to a bowl. Whisk for 2-3 minutes, scraping the bowl along the way, until smooth.
3. Pour in the warm ganache, and whisk for 1-2 minutes until combined and the mixture starts to look fluffy. The frosting will be runny
4. Place the frosting in the fridge for ~20 minutes, or until it thickens up into a spreadable consistency. Remove from the fridge at this point so it doesn't become too firm

Assembly and decoration

1. Once all components are cool, it's time to assemble. To start, use a sharp serrated knife to trim off the domes from the cake layers so they become completely straight. Place the cake trimmings into the freezer so you can grate them for decoration later
2. Transfer the piping to a piping bag. Place a cake layer onto a turntable or cake stand, and pipe a thick ring of frosting around the edges (see images above). Make sure there aren't any gaps in this ring. Then spoon half of the chocolate pudding onto the cake and spread it evenly, such that the ring of frosting holds the pudding inside and doesn't let it leak out
3. Cover with the next cake layer and repeat. Then cover with the last cake layer, and frost the cake with the frosting all over (you don't need to do a crumb coat for this cake as it gets covered in crumbs anyway). If at any point it feels like the cake layers are sliding around or the pudding is leaking out, quickly wrap the cake tightly in cling wrap and place in the fridge to firm up
4. Remove the cake trims from the freezer and use a zester or fine grated to turn it into fine crumbs. Fill your hand with cake crumbs and press it against the side of the cake so the crumbs can stick to the frosting. Repeat until the cake is coated in crumbs on the sides
5. Place in the fridge for at least 1 hours so the cake and pudding can properly set. Then slice, serve and enjoy!