Prepare the Oven and Cake Pan: Preheat your oven to 350°F (175°C). Grease and line a 9-inch round cake pan with butter and parchment paper to prevent the cake from sticking.
Melt the Chocolate and Butter: In a heatproof bowl, melt the chocolate and butter together. You can do this using a double boiler or in the microwave in short bursts. Stir until smooth and set aside to cool slightly.
Whisk the Eggs and Sugar: In a separate bowl, whisk together the eggs and sugar until smooth and slightly frothy. This helps the cake maintain its dense, fudgy texture.
Combine the Wet Ingredients: Gradually add the melted chocolate and butter mixture to the egg-sugar mixture. Stir until fully combined.
Sift and Add the Dry Ingredients: Sift the flour, cocoa powder, and salt into a separate bowl. Gradually fold the dry ingredients into the wet mixture, using a spatula to combine. Be careful not to overmix.
Bake the Gateau Chocolate: Pour the batter into the prepared cake pan and smooth the top. Bake for 25-30 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs. Allow the cake to cool in the pan for 10 minutes, then transfer it to a cooling rack.
Prepare the Ganache (Optional): For an extra layer of indulgence, make the ganache by heating the heavy cream until it starts to simmer. Pour it over chopped dark chocolate, let it sit for a minute, then stir until smooth. Pour the ganache over the cooled cake, allowing it to drip down the sides.
