I absolutely love Nigella's Coffee And Walnut Cake recipe. The texture of the cake is perfect. My question is if I can use this same cake recipe to make a chocolate cake by swapping out the espresso powder for cocoa powder. I know you have chocolate cake recipes but I love the texture of the coffee cake so much that I would want my chocolate cake to turn out the same. Thank you for your help.
Nigella's Coffee And Walnut Layer Cake (from KITCHEN) is a sponge cake that is enriched with ground walnuts and flavoured with espresso powder. Unfortunately we don't think that simply swapping the espresso powder for cocoa powder will really give the cake a deep chocolate flavour and adding extra cocoa could cause the cake to become a little dry, as cocoa powder absorbs a lot of moisture. But if you wanted to try then we would suggest replacing 40g of the flour with 40g cocoa powder (so use 160g flour and 40g cocoa powder). You could reduce the espresso powder to 1 teaspoon, as coffee and chocolate flavours complement each other.
If you wanted a chocolate cake with extra texture from ground nuts then alternatively you could add ground nuts to a chocolate cake recipe. We would suggest trying Nigella's Old Fashioned Chocolate Cake and replacing 50g of the plain flour with walnuts (so use 150g flour plus 50g walnuts). Grind the walnuts with the sugar in a food processor first and then add the remaining sponge ingredients and mix together, as directed in the recipe. We would, however, mention that as we have not tried either of these recipes in this form, we are unable to guarantee the results.