Preheat the oven to 180°C conventional heat and grease and line two 20 cm round cake tins.

Pour the hot brewed coffee over the 100 g chopped 70% dark chocolate and rest for 2 minutes.

Stir the coffee and chocolate until smooth, then leave it to cool slightly.

Mix the eggs, avocado oil, buttermilk, and vanilla extract at mixer speed 2/20 for about 30 seconds.

Sift the plain flour, cocoa powder, bicarbonate of soda, and baking powder into a separate bowl.

Stir the caster sugar and 5 g fine salt into the sifted dry ingredients.

Add half of the dry ingredients to the wet mixture and mix at speed 1/20 only until combined.

Add the remaining dry ingredients and mix at speed 1/20 just until no dry flour remains.

Gradually pour in the cooled coffee-chocolate mixture while mixing at speed 1/20.

Mix briefly until the batter is smooth and evenly combined.

Divide the batter evenly between the prepared tins and level the surfaces.

Bake for 25 to 30 minutes, until a skewer comes out with moist crumbs but no wet batter.

Cool the cake layers completely on a wire rack before filling.

Place 600 g dark chocolate in a clean mixer bowl.

Heat 500 ml thickened cream until steaming and almost simmering, then pour it over the dark chocolate.

Rest the ganache for 2 minutes, then mix at speed 1/20 until smooth.

Add the softened unsalted butter and 2 g fine salt, then mix briefly until combined.

Cool the ganache until thick and spreadable; if refrigerating, stir it every 10 to 15 minutes for about 120 minutes.

Reserve 300 g ganache for the filling and keep the remaining ganache unwhipped for coating.

Chill the reserved ganache until thick but still soft.

Whip the reserved ganache at speed 2/20, then increase to approximately speed 8/20.

Bloom the gelatine powder in 60 ml cold water for 5 minutes.

Heat 150 ml thickened cream, 210 g caster sugar, 75 ml water, and 70 g cocoa powder in a saucepan until smooth and steaming.

Remove the glaze mixture from the heat and stir in the bloomed gelatine until fully dissolved.

Cool the mirror glaze until slightly thickened but still pourable, about 30 to 35°C.

Level the cooled cake layers if needed, then spread the whipped ganache between them.

Coat the stacked cake with the unwhipped ganache and chill until firm.

Pour the cooled mirror glaze over the chilled cake and let the excess drip off.

Chill the finished cake until the glaze is set, then slice and serve.