Espresso For Coffee Walnut Cake

Our answer

Nigella's Coffee And Walnut Layer Cake (from KITCHEN) has a sponge that includes ground walnuts and espresso powder and a coffee buttercream that is also flavoured with espresso powder. Whilst you could substitute stovetop coffee, it is not as strong as instant coffee and if you add too much extra liquid (to get a stronger coffee flavour) then this will affect the cake and make the icing too runny.

Instead we would suggest that you use instant coffee granules, dissolved in some hot water from a just-boiled kettle. For the cake substitute the espresso powder with 4 1/2 teaspoons of instant coffee dissolved in 2 tablespoons of hot water. You are unlikely to need to add the 1-2 tablespoons of milk at the end to get the batter to a soft dropping consistency, so do check before adding any milk. For the buttercream use 2 3/4 teaspoons of instant coffee granules dissolved in 1 tablespoon of hot water.