Start by preheating your oven to 160°C (320°F). Prepare your cake pan by greasing it with butter or a little oil, then line the bottom with baking parchment so the cake won’t stick.

Next, melt the chocolate and butter together. Place the butter and chocolate in a medium saucepan over low heat. Add a pinch of instant coffee to enhance the chocolate flavor. Stir constantly until everything is fully melted and smooth. Take the pan off the heat and let the mixture cool slightly.

While the chocolate mixture cools, mix the wet ingredients. In a large bowl, whisk together the eggs, caster sugar, brown sugar, and vanilla until the mixture is a little fluffy. Slowly pour in the melted chocolate and butter, stirring continuously until it blends completely.

Now prepare the dry ingredients. In a separate bowl, sift together the flour, cocoa powder, baking powder, and salt.

Combine the wet and dry ingredients. Gradually fold the dry mixture into the wet mixture, adding the milk a little at a time. Stir gently until the batter is smooth and glossy, with no lumps. Be careful not to over mix.

Pour the batter into the prepared cake pan and smooth the top with a spatula so it’s even.

Bake the cake in the preheated oven for 60–70 minutes. Test for doneness by inserting a skewer into the center; it should come out mostly clean with a few moist crumbs. Be careful not to over bake the cake should stay dense and fudgy.

Let the cake cool in the pan for 10–15 minutes, and then transfer it to a wire rack to cool completely before frosting.

To make the frosting, melt some butter in a small saucepan over low heat. Stir in cocoa powder, milk, and vanilla until smooth. Gradually sift in icing sugar while beating, until the frosting is creamy and easy to spread.

Finally, frost the cooled cake. Use a spatula to spread the frosting evenly over the top and sides. You can smooth it out or create swirls for a decorative finish.