Preheat and prep. Set your oven to 190°C (170°C fan) and line a 12-hole muffin tin with paper cases. The cases should stand slightly proud of the tin — this helps the muffins rise upward rather than spilling over the sides.

Whisk the dry ingredients. In a large bowl, sift together the flour, cocoa powder, baking powder, bicarbonate of soda and salt. Whisk them lightly — you’ll see the cocoa dust rise in a dark cloud, and the mixture should feel silky and uniform with no lumps of flour or cocoa.

Blend the wet ingredients. In a separate jug or bowl, whisk the eggs, both sugars, oil, buttermilk and vanilla until the mixture is pale and slightly thickened, about 30 seconds of vigorous whisking. It should smell sweet and faintly tangy from the buttermilk.

Combine wet and dry. Pour the wet mixture into the dry and fold with a rubber spatula until just combined — streaks of flour are fine at this stage. The batter will be thick, glossy and smell deeply of chocolate. Do not overmix; a few lumps are your friend.

Add the peanut butter and chocolate. Drop spoonfuls of peanut butter over the batter, then scatter in the dark chocolate chips. Fold three or four times only — you want visible ribbons of peanut butter and pockets of chocolate throughout. The batter should look marbled, not homogenous.

Rest the batter. This is the non-negotiable step. Cover the bowl and let the batter sit at room temperature for 15 minutes. During this time, the starches in the flour hydrate and the baking powder activates. You’ll notice the batter thickens slightly and becomes even glossier.

Divide and fill. Use a large ice-cream scoop or two spoons to divide the batter evenly among the 12 cases. Fill each case to the very top — almost overflowing. The batter should mound slightly above the rim; this is what gives you that high, domed top.

Bake. Place the tin on the middle rack and bake for 18–20 minutes. At 18 minutes, insert a skewer into the centre of a muffin — it should emerge with a few moist crumbs clinging to it, not wet batter. The tops should spring back when lightly pressed, and the kitchen will smell like a chocolate factory.

Cool in the tin. Let the muffins rest in the tin for exactly 5 minutes. They will be very tender and fragile straight out of the oven; this short rest allows them to set. Then transfer them to a wire rack to cool completely. You’ll hear a faint crackling sound as they cool — that’s the sugar crystallising on the domed tops.