Preheat your oven to 180°C (350°F). Grease and line a round 20cm (8-inch) cake tin with parchment paper.
Cream the Butter and Sugar
In a large bowl, beat the butter and caster sugar together until pale and fluffy.
Add the Eggs and Flavorings
Add the eggs one at a time, beating well after each addition. Stir in the orange zest and juice.
Mix the Dry Ingredients
Sift the self-raising flour and cocoa powder into the bowl. Gently fold them into the mixture until combined.
Bake the Cake
Pour the batter into the prepared tin and smooth the top. Bake for 35-40 minutes, or until a skewer inserted into the center comes out clean. Allow the cake to cool in the tin for 10 minutes, then transfer it to a wire rack to cool completely.
Make the Chocolate Ganache
Heat the double cream in a small saucepan until just simmering. Remove from heat and pour over the chopped dark chocolate. Let sit for 1-2 minutes, then stir until smooth. Add the orange juice and mix well.
Assemble the Cake
Spread the ganache evenly over the cooled cake, allowing it to drip down the sides. Decorate with orange slices, zest, or chocolate shavings as desired.
Serve and Enjoy
Slice and serve the cake with a cup of coffee or as a delightful dessert after a meal.
