Frosted Walnut Layer Cake

Walnut trees were cultivated in Persia (now Iran) as early as 7000 BC. In fact, they may have been included in the Hanging Gardens of Babylon. The walnuts we know today, originally called Persian walnuts, were brought to England along the Silk Road. Eventually, English merchant marines began using this hardy, shelf-stable cargo to trade in ports throughout the Mediterranean, thus earning it the moniker English walnut.

Using nuts in culinary applications goes much further back, however. Archaeologists in Israel found evidence that nuts were part of man’s diet 780,000 years ago. There’s even a recipe for a Tiger Nut Cake printed in hieroglyphs in the Tomb of Rekhmire, in Thebes, Egypt, dating back to 1400 BC. (Though technically tiger nuts are tubers and not true nuts, I thought that little factoid was so interesting I wanted to include it.)

Fortunately, Mary Berry’s version of a nut cake, which we are making today, is much lighter and fluffier than that of the ancient Egyptians, thanks to the addition of eggs and baking powder. Her cake features three layers of light, moist sponge with bits of walnut throughout, filled with vanilla buttercream and covered with what she calls boiled icing but what I recall from my childhood as seven-minute frosting.

This fluffy, white, meringue-like frosting is not boiled at all, but whisked over a pan of simmering water until it forms a marshmallowy consistency. (I remember, as a kid, standing by the hot stove for what seemed like hours, whisking the sweetened egg whites until my arms ached.) Once done, it certainly looked pretty swirled all over the cake like a cloud, but I had the same problem most of the bakers in the Great White Tent did in that my frosting came out grainy. I’m not sure how this could have been corrected; if I had continued to beat it longer over the bain-marie I’m afraid it would have been too stiff.

In addition to the cake and frosting, Mary wanted to see caramelized walnuts on top. I have had difficulties making caramel in the past, but I think I’m getting the hang of it. While I’ve had more luck with the dry method, Mary’s recipe uses the wet method, adding 2 tablespoons of water to the sugar before melting it. Having failed at this method in the past, I’ve done a bit of research and learned a few tricks of the trade. So instead of stirring the sugar to try dissolving it in such a small amount of water, I simply poured the water over the sugar and began heating it without stirring. I also put the lid on the pan to help prevent sugar crystals from forming on the sides of the pan, which can cause the entire batch to crystallize. Lifting the lid occasionally, I would also brush the sides of the pan with water if I saw any hint of crystals forming. This time it worked, and I ended up with a nice golden caramel perfect for coating walnuts. I even had enough left over to make some caramel curls by wrapping the cooling caramel around a greased knife-sharpening steel. I used these as added decorations, similar to Ugne’s caramel work on her walnut cake.

The cake itself is not difficult to make. Mary’s instructions to the bakers to “read the recipe twice” and “weigh carefully” is good advice for any baker to follow, no matter how experienced. I did alter it a bit by using three 6-inch pans instead of 8-inch, since I don’t have three 8-inch pans. But because my 6-inch pans are 3 inches deep, I didn’t have to reduce the amount of batter, and they took about the same amount of time to bake as thinner 8-inch layers. If you ever need to scale a recipe to fit different-sized cake pans, I recommend this site.

Most of the Bake-Off bakers did a good job on this technical challenge (despite the grainy frosting), and I think mine could stand up to any of theirs. I got some nice compliments from the neighbors and friends I shared it with, but in my opinion, this type of frosting is just too sweet. I know this is a matter of personal taste — one friend I shared my cake with commented that the icing was a nice change from the “powdered sugar type.” But if I were to make this cake again (and I definitely will!), I would serve it unfrosted, perhaps with a sprinkling of powdered sugar just to make it pretty. It really doesn’t need anything more!

You can find Mary Berry’s recipe here, but I have adapted it for American bakers below.

Up next: Black Forest Gâteau