Preheat your oven to 350°F (175°C) and grease three 8-inch (20cm) cake pans, lining the bottoms with parchment paper.

In a large bowl, whisk together the flour, sugar, dark cocoa powder, baking soda, baking powder, and salt.

In a separate bowl, whisk the eggs, buttermilk, and vegetable oil. Fold the wet ingredients into the dry ingredients until just mixed. Slowly pour in the hot coffee while stirring continuously.

Divide the batter evenly among the prepared pans. Bake for 30-35 minutes until a toothpick inserted into the center comes out clean. Cool in pans for 10 minutes, then turn out onto wire racks to cool completely.

In the chilled bowl of a stand mixer, combine the cold mascarpone cheese, powdered sugar, fresh orange juice, and fresh orange zest. Beat on medium speed until smooth.

Slowly pour in the cold heavy cream while the mixer is running. Increase the speed to high and whip until stiff peaks form.

Place finely chopped dark chocolate in a heat-proof bowl. Heat 1/2 cup (120ml) of heavy cream in a saucepan just until simmering, then pour over the chocolate.

Let sit undisturbed for 5 minutes. Add the light corn syrup, then gently whisk starting from the center outward until smooth and glossy. Let cool slightly to a dripping consistency.

Place the first dark chocolate sponge layer on a plate. Spread half of the pale orange cream filling evenly across the surface. Top with the second layer and repeat with remaining filling. Top with the final cake layer.

Pour the slightly cooled ganache over the top of the cake. Use the back of a spoon to gently nudge it over the edges to create thick drips down the sides.

Arrange the fresh half-moon orange slices in a crescent shape along one side of the top. Scatter the fine orange zest curls over the ganache. Let set for 15 minutes before slicing.