Step 1

Pre heat the oven to 180°C/160°C fan/gas 4 then grease a 20cm tin and line it with baking parchment. Put the plain flour, caster sugar, cocoa powder, bicarbonate of soda and salt into a large bowl. Whisk to combine.

Step 2

If you don’t have buttermilk, pour the milk into a large jug and add the lemon juice. Leave to stand for five minutes until thickened.

Step 3

Whisk the buttermilk/acidified milk into the melted butter and egg followed by the coffee or water.

Step 4

Pour the wet mixture into the dry ingredients, whisking until a smooth batter has formed. It will be very runny, and if you are making more than one layer, the best way to divide it between the tins is to transfer the batter to a large jug. You can then use either the markings on the jug to measure the amount going into each tin, or put a tin on the scales and measure by weight. It is important to do this so that the layers are the same height and cook at the same rate.

Step 5

Bake for 25–30 minutes until risen and a skewer inserted comes out clean. Leave to cool in the tin for ten minutes before turning out onto a cooling rack.