Can I Make The Chocolate Guinness Cake As A Sheet Cake?

Our answer

Nigella's Chocolate Guinness Cake (from FEAST) is a moist chocolate sponge that is baked in a 9-inch springform pan. These pans are usually around 3 inches deep and have a volume of about 12 cups. A standard half sheet pan is usually 18 x 13 inches and 1 inch deep and has a volume of around 14 cups. This would suggest that you only need to increase the cake batter quantities by 15%, but as this is a relatively difficult amount to measure, you would probably need to use just a single quantity of the batter.

However, the sheet cake will be much thinner than the round cake and our main concern is that it will end up being too dry after baking, even though the baking time will be much shorter (it could be as short as 15-20 minutes). So we would prefer not to bake the Chocolate Guinness Cake in sheet pan form. If you wanted a rectangular cake it may be better to bake the cake mixture in a 13 x 9 x 2-inch rectangular cake pan as the cake will be a little deeper. The baking time is likely to be 35-45 minutes. In theory you would need to double the quantity of frosting for the rectangular cake. But as the rectangular cake is less deep than the round version, it may mean too much frosting so we suspect that you would need no more than 1.5x the frosting quantity. But please note that as we have not tried the cake in either of these pans, we are unable to guarantee the results.