Roasted Sweet Potato Layer Cake

I’m about to make this cake for the third time in as many weeks. I made it to begin with because our wonderful au pair, our fourth (and best behaved) child, our lifesaver extraordinaire, Aurora, is in the middle of a love affair with sweet potatoes. Growing up in Italy, she had never seen, tasted or heard of sweet potatoes before coming to live with us about 18 months ago. And now? She’s obsessed. So we make a lot of sweet potatoes and I’ve been reminded how easy and delicious they are to make. You can just chop them, without peeling, and roast them in some oil and salt for 20 minutes and BOOM – sweet potato fries (not exactly crispy, but not exactly a problem). You can peel and boil them and BOOM – a delicious side dish you can dress up with pretty much anything. Cayenne and maple syrup. Herbes de Provence and minced garlic. Grated cheese. Marshmallows. Good old fashioned salt and pepper. They’re versatile, they’re healthy, they’re easy to keep in the fridge for months until you remember to do something with them. It’s easy to see how someone just learning of the humble yam might become a little taken.

Because she loves sweet potatoes so much and so enthusiastically, I decided to be less conventional and put it in dessert. Vegetables in a dessert is about as Italian as sweet potatoes so naturally Aurora was shocked and a little bit appalled. Until she tried it.

Now it’s on request for baby showers and dinner parties. Before I know it, it will replace chocolate cake as our family’s go-to for birthdays. Its slight warmth from the cinnamon, nod to Thanksgiving from the yams, and bright orange color make it the perfect cake to make this autumn. It really is a centerpiece kind of cake, the kind of cake you can serve at Thanksgiving to even the pie purists. The kind of cake that will remind you why baking cakes is worth it at all.

ROASTED SWEET POTATO CAKE

This recipe may look a little familiar if you’re a true lifelong follower of this blog. In fact, I published a nearly identical and much beloved recipe with squash back in 2010. The sweet potato rendition is very similar and it’s one of our all-time favorites; if I ever had to enter a cake contest based on flavor, this humble beauty would be my entry. Frost with cream cheese frosting and/or the buttercream frosting recipe below, maybe adding a few cheeky spoonfuls of puree to the batch for color and flavor. 

Serves 12

2 cups flour
1 cup sugar
2 teaspoons baking soda
1 teaspoon cinnamon
1 teaspoon salt

3 eggs
1 cup oil (or a mixture of mostly oil topped up with pureed sweet potato)
2 teaspoons vanilla extract
2 cups pureed roasted sweet potato (from about 5 large sweet potatoes)*

Preheat oven to 350F (180C). Butter and flour two springform pans.

In a large bowl, sift the flour, sugar, baking soda, salt and spices together.

In another bowl, mix the eggs, oil and vanilla.

Using a wooden spoon, combine the egg mixture with the flour mixture until just combined, then add the sweet potato puree and mix gently until completely combined. Evenly divide the batter between the prepared pans and bake in the preheated oven for about 30 minutes or until a toothpick inserted in the middle comes out clean. Cool in the pans; when cakes are completely cooled, generously frost each layer with my favorite cream cheese frosting or the amazing buttercream frosting that follows below!

* If you’re making your own sweet potato puree (and you should! You’ll just need to do it a minimum of an hour or so in advance), simply preheat the oven to 200C/400F. Peel the sweet potatoes and chop them into evenly sized pieces. Roast them on a foil-lined tray for 30 – 45 mins, or until soft. It’s completely fine to roast them “dry”, without any oil, but if you want to make them sing, roast them with some butter or oil on top. Plop your soft sweet potato chunks in a bowl and use an immersion blender to puree completely. You can make the puree up to a week ahead, just keep it in the fridge.

AMAZING BUTTERCREAM FROSTING

This ridiculously delicious frosting can be used to cover and fill any cake and can easily take a little something extra (lemon extract or zest, some cocoa, etc.) Makes enough to frost the inside and outside of a 2-layer cake. Can be made a few days ahead and stored in the fridge. Make sure it’s not cold when you go to use it, as it won’t spread. Oh, and you don’t need to refrigerate a cake frosted with this buttercream – it’s mostly butter and won’t go off! (NB: this buttercream isn’t pictured in the photos, which show off the cream cheese frosting, but shhhh the buttercream is actually a little prettier.)

1 cup (225 grams) salted butter, softened to room temperature

4.5 cups (approx) confectioner’s/icing sugar (based on sweetness)

1/2 teaspoon fine salt

1 teaspoon vanilla extract (optional)

1/3 cup heavy/double cream (or substitute mascarpone)

Beat the softened butter in a large bowl for a few minutes until it becomes very light-colored and fluffy. Add the confectioner’s sugar, cream and vanilla. Beat for about 4 minutes. You can add some sweet potato puree or spice if you want to make it extra autumnal.