Rich Chocolate Loaf Cake

Remove the chocolate bowl from the saucepan. Place the heavy cream in the still-warm water to gently warm it. Add the egg yolks to the chocolate mixture one at a time, mixing well after each addition, then add the warm heavy cream in 4 additions, stirring until smooth each time.

Continue stirring the chocolate mixture for about 6 minutes, until it becomes thick, glossy, and slightly lighter in color. This helps the mixture emulsify properly.

Make a warm water bath for the chocolate mixture by combining 300 ml boiling water with 300 ml room-temperature water in a larger bowl or container. Set the bowl of chocolate mixture into the warm water to keep it fluid while you prepare the meringue.

Take the chilled egg whites from the refrigerator and beat them briefly until loose and foamy. With a hand mixer on high speed, whip until white and fluffy. Add one-third of the sugar, beat for 30 seconds, then add the rest of the sugar and continue beating until very soft peaks form. Finish by mixing on low speed for 1 minute to even out the texture.

Transfer the warm chocolate mixture to a large mixing bowl. Fold in one-third of the meringue to lighten the batter.

Sift the flour and cocoa mixture over the batter again. Whisk gently until just combined, then give the batter a few quick strokes to fully smooth it out.

Fold in half of the remaining meringue with a spatula until mostly combined, then fold in the rest just until no large streaks remain. Add the rum and fold a few more times until incorporated.

Pour the batter into the chilled loaf pan and level the top. Tap the pan lightly on the counter about 10 times to remove large air bubbles.

Place the loaf pan inside a larger baking pan. Pour in hot water, about 50°C (122°F), until it surrounds the loaf pan to create a water bath. Bake for 40 minutes at 150°C (302°F).

Carefully remove the loaf pan from the water bath and let the cake cool for 5 minutes. Cover the top loosely with plastic wrap and let it rest for 1 hour so it cools gradually and settles evenly.

After 1 hour, wipe away any condensation from the plastic wrap, then re-cover the cake. Refrigerate for at least 3 hours to firm up the texture.

Run a warm knife around the edges to release the cake from the pan. Smooth the sides with the warm knife if needed, then dust the top with cocoa powder before serving.