Oven - Preheat the oven to 325℉/ 165℃ or Gas Mark 3.Grease and line 3 x 8-inch round cake pans or 2 x 9-inch round cake pans with parchment paper and dust with cocoa powder

Dry ingredients - In a large bowl sift or combine together the flour, baking powder, baking soda, and salt. Set aside

Cocoa paste - In a medium bowl combine the hot water with cocoa powder and coffee. Set aside to cool

Whip - Whip the eggs for a minute in the bowl of a stand mixer with the whisk attachment on medium speed. Then, gradually add the sugar, a few tablespoons at a time. Once all the sugar is in, whip until the eggs are light and foamy or ribbon stage.

Wet ingredients - Next, add the cocoa paste to the whipped egg mixture, followed by the sour cream, buttermilk, and vanilla extract. Then, gradually add the oil, and do not overmix. Pro tip - before adding the sour cream and buttermilk whip them together with a whisk to make sure there are no lumps.

Wet to dry - Add the flour mixture to the wet ingredients and combine well. But do not overmix.

Bake - Divide the batter equally between the prepared cake pans. Transfer the pans to preheated oven on the center rack. Bake for about 30 to 35 minutes until a toothpick inserted in the center comes out clean.

Cool - When baked, cool in the pan for 10 minutes, then invert on a cooling rack and cool completely before baking.

Chocolate - In the microwave-safe bowl or double boiler melt the chocolate – set aside to cool until barely warm.

Cream - In the bowl of a stand mixer with the paddle attachment, cream the butter for a minute. Add salt, whipping cream, and vanilla extract – continue to whip for a minute more.

Sugar - Next, add the powdered sugar one cup at a time. Once all the powdered sugar has been incorporated, turn the mixer up to medium-high. Continue to mix for 2 to 3 minutes more until you have a light and fluffy buttercream that looks similar to a whipped cream consistency.

Chocolate buttercream - Now, add the melted and cooled chocolate. Make sure to scrape the bottom and sides to ensure you have a smooth chocolate buttercream with no white streaks.

Microwave - In a microwave-safe bowl add the chopped chocolate and heavy cream. Melt for a minute or two until smooth. Add the butter and vanilla extract. Combine well. Stovetop - Place the cream in a saucepan and bring it to an almost boil. Pour the heavy cream over the chopped chocolate into a large bowl. Combine until smooth. Add the butter and vanilla extract. Combine well.

Rest - Cover with ganache with plastic wrap making sure to cover the surface of the chocolate to prevent any skin from forming. Leave to set in the fridge for 2 to 3 hours or on the counter for 4 to 6 hours until it’s about peanut butter consistency.

Level - Once cooled, cut the domes off the cake layers with a serrated bread knife or cake leveler. Brush each layer with simple syrup on both sides.

Stack - Place a cake layer on the cake board or cake stand. Top with about a large dollop of buttercream and spread evenly using a spatula. Place the second layer followed by more buttercream and then the last layer.

Chill - Transfer the stacked cake layers to the fridge and chill for 10 minutes so the buttercream holds the layers together.

Frost - Add a large heap of ganache to the cake. Spread evenly with an offset spatula. Add more ganache on the sides with a straight-edge spatula. Use a bench scraper to smooth the sides. Place in the fridge while you make the drip.

Drip - Melt about a cup of the leftover ganache in the microwave for 10 seconds until runny and smooth. Let cool until barely warm. Place the melted ganache in a piping bag. Make a small hole so you are in control of the bag. Chill until set (30 minutes at least)

Pipe - Place the remaining chocolate buttercream in a piping bag with a large star piping tip. Pipe a border. I made circular swirls as shown in the video.

Sprinkles - Decorate the top and bottom with sprinkles or similar as desired.