Step 1

Pour the stout into a large measuring jug to come up to 400ml/14fl oz; you will need to wait for the frothing to subside. If you think about it ahead of time, it might be wise to open the bottle a bit earlier. Don’t drink the remaining 100ml/3½fl oz yet, as you may need some of it shortly. When the beer’s calmed down enough to be measured clearly, add the egg white (reserving the yolk in a little covered bowl in the fridge for the egg wash the next day), followed by the sugar, the oil, and then the treacle. Stir or whisk gently to mix, as it may fizz up a bit.

Step 2

Mix the flours, cocoa, activated charcoal (if using), seeds, yeast and salt in a large bowl.

Step 3

Give your jug of dark liquid another stir, then pour a third into the bowl and mix. Repeat until all the liquid is used up. You may still need to use more liquid, so slowly stir in as much of the remaining stout as you need to form a sticky mixture. It won’t look very dark: until it’s baked, it has the buff colour of cookie dough, unless you’re adding activated charcoal, in which case it will be cowpat brown. Cover with cling film (or a shower cap) and leave it in the kitchen for 16–20 hours, until it has increased in volume, has a slightly spongy texture and is bubbly on top.

Step 4

Grease a sturdy 2lb/900g loaf tin and line the base with baking parchment. Scrape the bread dough into the tin, smoothing it very gently out to the edges and on top. Drape a clean tea towel over the tin and leave for 2 hours. It will rise a little, but not much. Towards the end of this time preheat the oven to 220C/200C Fan/Gas 7.

Step 5

Add a teaspoon of cold water to the reserved egg yolk and mix with a little whisk or a fork, then dab a pastry brush into the yellow goo and lightly paint the surface of the bread. I can’t honestly say you use much of this yolk; if, like me, you find waste difficult, then keep it to add to a couple of eggs for scrambling.

Step 6

Sprinkle the teaspoon of nigella seeds on top and put the tin into the oven, immediately turning the heat down to 200C/180C Fan/Gas Bake for 40 minutes, then (wearing oven gloves, and perhaps giving a nudge around the edges with a small palette knife) slip it out of its tin. It will feel almost cooked, but it is a dense, weighty loaf: don’t expect white-bread lightness; even when fully cooked, this loaf feels as heavy as a brick. Give the loaf a knock underneath: it probably won’t sound hollow, but register the sound.

Step 7

Put the loaf, out of its tin, back into the oven directly on the shelf for 10–15 minutes, by which time it will feel firm, but still with a bit of give at the sides and, when you knock it underneath, it will sound, if not exactly hollow, then hollower than it did before. Allow to cool completely on a wire rack before even thinking of cutting into it.

Step 8

Serve slices topped with smoked salmon and dill.