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• Natural cocoa and baking soda, not Dutch cocoa and powder. Natural cocoa is acidic; the soda neutralises it, and the reaction is both the lift and the colour shift. Use Dutch-process here and you get a good cake that is not this one. See Cocoa and cocoa mixes.
• Bloom the cocoa in boiling liquid. Hot water or coffee poured over the cocoa dissolves the solids and releases aromatics that stay locked up in a dry mix.
• Coffee, not for flavour. It amplifies chocolate and disappears; see coffee.
• Buttermilk for tenderness and tang. Its acid also keeps the crumb soft; see buttermilk recipes.
• Do not overbake. Two minutes past done and a chocolate cake goes dry irreversibly. Pull it when a skewer has moist crumbs, not when it is clean.

Two 20 cm layers. Serves 12.

• 85 g natural cocoa powder
• 240 ml boiling water or hot coffee
• 225 g unsalted butter, softened
• 300 g light brown sugar
• 100 g granulated sugar
• 3 eggs
• 2 tsp vanilla — see Pure vanilla extract
• 280 g all-purpose flour
• 8 g baking soda
• 5 g fine salt
• 180 ml buttermilk

Frosting — chocolate fudge:

• 300 g dark chocolate, chopped — see Chocolates
• 300 ml double cream
• 60 g unsalted butter
• 40 g honey or golden syrup

Heat the oven to 175 °C / 350 °F. Butter and line two 20 cm tins.

Whisk the cocoa into the boiling liquid until smooth and set it aside to cool to lukewarm.

Cream the butter and both sugars four minutes. Beat in the eggs one at a time, then the vanilla.

Alternate the flour, soda and salt with the buttermilk in three additions, then mix in the cooled cocoa liquid. The batter is thin.

Divide by weight and bake 28–32 minutes, until a skewer shows moist crumbs. Cool ten minutes in the tins, then turn out.

For the frosting, pour hot cream over the chocolate, stand two minutes, stir smooth, then beat in the butter and honey. Cool until spreadable, about an hour at room temperature.

• The reddish tint is real and comes from anthocyanins in natural cocoa at higher pH. It is also the ancestor of red velvet cake, which is what happened when bakers pushed the effect with dye.
• Three thin layers look better than two thick ones and bake in 22 minutes.
• Keeps four days at room temperature under a dome. Refrigerating a butter-frosted cake makes it hard; bring it back to 20 °C before serving.

Method and theory: Cake recipes · cakes · Cocoa and cocoa mixes · yeast and leavening

Nearby: red velvet cake · texas sheet cake · german chocolate cake