Preheat your oven to 155°C (310°F) / 135°C fan / gas mark 3.
Grease two 20cm / 8-inch springform cake tins with butter and line the bases with baking parchment.
In a large mixing bowl or a stand mixer, whisk the eggs, oil, and muscovado sugar until well combined.
Add the self-raising flour, instant coffee, and salt to the bowl.
Beat until the batter is smooth and thoroughly combined.
Divide the batter evenly between the two prepared tins.
Bake for 35–40 minutes, or until a skewer inserted into the centre of the cakes comes out clean.
Let the cakes cool in their tins for 10 minutes before carefully turning them out onto a wire rack to cool completely.
While the cakes are cooling, prepare the glaze.
In a small bowl, mix the granulated sugar, instant coffee, and 3 tbsp (45 ml) of boiling water, stirring until the sugar has completely dissolved.
Once the cakes are out of their tins, use a skewer to prick them all over the top. Use a pastry brush to generously apply the coffee glaze over both cakes. This step adds moisture and a huge flavour boost.
To make the icing, beat the softened butter and room temperature cream cheese in a large bowl until smooth. Sift in the icing sugar and cocoa powder, and beat again until light and fluffy.
Gently fold in the 20g (0.71 oz) of cocoa nibs, reserving a few for decoration at the end.
To assemble, place one cake layer on your serving plate.
Spread half of the icing evenly over the top.
Place the second cake layer on top and generously coat the top with the remaining icing. Decorate with the reserved cocoa nibs and an optional dusting of cocoa powder before serving.
Don't skip the coffee glaze! It's the secret to an incredibly moist cake and intensifies that delicious mocha flavour.