Can I Make A Chocolate Frosting For The Chocolate Guinness Cake?

Our answer

Nigella's Chocolate Guinness Cake (from FEAST) is a dark and moist chocolate cake that is topped with a whipped cream and cream cheese frosting. Nigella has tried versions of the cake with a chocolate icing, but it does slightly detract from the rich flavour of the cake and the visual contrast of the white frosting and dark cake is lost. So our preference is to leave the cream cheese frosting as it is.

However, if you do need to make a chocolate version of the frosting, we suspect that using melted dark chocolate may be the best option. Cocoa powder is quite bitter and also can give the frosting a slightly grainy finish unless you mix the cocoa powder with boiling water first. Melted dark chocolate will not have such an impact on the sweetness of the frosting and should give a slightly firmer frosting than adding cocoa mixed with water. We would estimate that you would need to use around 125g (4 ounces) of good-quality dark chocolate (60-70% cocoa solids). Melt the chocolate via your preferred method then cool and add to the cream cheese once you have beaten in the icing (confectioners') sugar and cornflour (cornstarch) and before you add the whipped cream. Make sure that the cream cheese mixture is not too cold before you add the chocolate, as if it is cold then this could cause the chocolate to set into small lumps as it is mixed in. Please note that as we have not tried the frosting in this form ourselves, we are unable to guarantee the results.