Preheat the oven to 180 (350f) and prep a 9-inch springform pan with cooking spray and parchment paper.

Into a large mixing bowl, add the eggs, buttermilk, oil, vanilla extract, kosher salt, granulated sugar, sour cream, sift the cocoa powder, and mix with a whisk until well combined.

Sift the flour, add the baking powder, and baking soda, and mix until almost combined.

Add the hot coffee and mix until the batter is smooth and there are no large lumps of flour visible.

Pour the cake batter into the baking pan and bake in a 180c (350f) preheated oven for 22-25 minutes or until a toothpick inserted into the cake comes out clean with a few moist crumbs.

Remove the cake from the oven and allow it to cool completely to room temperature.

In a small bowl, add the water and the gelatin and allow it to sit for 10 minutes for the gelatin to bloom.

Melt the dark chocolate and heavy cream in a medium mixing bowl. You can do so in the microwave for 20-10 second pulses and mix between every pulse. Or melt it in a bain marie method.

Mix the melted chocolate and heavy cream with a whisk or with an immersion blender to ensure it's smooth and the emulation is perfect.

In a large mixing bowl, add the cold heavy cream, sifted cocoa powder, powdered sugar, and vanilla extract, and whip to soft peaks, resembling a yogurt consistency.

Melt the gelatin in the microwave for 5 second pulses until it's fully melted, do not overheat it! Add the melted gelatin to the melted chocolate and heavy cream mixture and mix until well combined.

Add about ½ cup of the mousse mixture into the melted chocolate mixture and mix it until smooth and combined.

Add half of the chocolate mixture to the whipped cream mixture and gently fold it with a rubber spatula until it's mostly combined.

Add the other half and fold it until the mixture is smooth and homogeneous and doesn’t have streaks of chocolate. Try not to fold it too much to retain the air in the whipped mixture.

Once the cake has cooled completely, remove the ring from the cake and level off the top of the cake with a serrated knife or a cake leveler.

Line the cake pan with a sheet of acetate to create a cake collar, which will hold in the mousse and ensure clean sides once the cake has chilled.

Slide the acetate down the sides of the pan until it reaches the bottom, gently nudging it between the cake and the pan wall.

Then pour the mousse over the cake, filling it to the top of the springform pan. The cake collar must extend about an inch above the pan.

Smooth it out with an offset spatula and allow it to set in the fridge for at least 5 hours, ultimately overnight.

Melt dark chocolate and heavy cream in a small to medium mixing bowl in the microwave for about 70 seconds.

Let the chocolate and the cream sit for 10 minutes for the chocolate to melt, then mix until the chocolate ganache is smooth and silky.

Remove the ring and the acetate sheet pour the slightly warm ganache on the middle of the cake, and smooth it out with an offset spatula to nudge it to the sides and over the edge of the cake.

Chill the cake in the fridge for another 30 minutes, to allow the ganache to set, slice, and enjoy!