Heat sugar and water in a small saucepan over medium heat, swirling the pan (not stirring) until it turns deep amber, about 6-8 minutes.

Pour the caramel immediately into a 20cm (8-inch) round mold, tilting to coat the bottom and slightly up the sides. Set aside to harden.

Heat oven to 150C/300F. Crush amaretti cookies into fine crumbs using a food processor or a rolling pin and sealed bag.

In a large bowl, whisk eggs and sugar together until pale, about 2 minutes.

Whisk in cocoa powder, crushed amaretti and rum until smooth and no dry lumps remain.

Warm the milk in a saucepan until steaming but not boiling, then whisk it slowly into the egg mixture.

Strain the custard through a fine-mesh sieve into the caramel-lined mold to remove any lumps.

Set the mold in a roasting pan and pour boiling water into the pan until it reaches halfway up the sides of the mold.

Bake for 50-55 minutes, until the edges are set and the center still jiggles slightly, like a baked cheesecake. Internal temp should read 176F/80C.

Remove from the water bath, cool to room temperature, then refrigerate for at least 4 hours, ideally overnight.

Run a thin knife around the edge, set a rimmed plate on top and invert quickly to unmold, letting the caramel run down as sauce.