Sweet potatoes in a cake? Is that legit? I thought sweet potatoes were the platform for marshmallows, not a brown sugar streusel.
I was dubious of sweet potatoes being successfully turned into cake but ended up delightfully surprised. This works! The cake is moist and pound cake heavy but not at all sodden. The spices play coy in their subtle support of the sweet potato star of the show. The ingredients play with perfect synergy in this surprisingly delightful cake.
The key to taking the potential sodden weight out of this cake is to bake the sweet potatoes in their jackets. The original recipe called for 2 cups of cooked, mashed sweet potato leaving the method of cooking up to the baker. Experience taught me to bake the sweet potatoes; DO NOT BOIL them. Save the boiling method for sweet spuds covered in marshmallows.
The cake is straightforward to put together if you bake the sweet potatoes the day ahead. I like to bake a couple of extra potatoes when making a pork and sweet spuds dinner. I eat one sweet spud and mash up the extra three for next day cake.
BTW the streusel-ly topping makes the cake.
3 medium sweet potatoes
1 cup butter, unsalted
1 cup granulated sugar
1 cup brown sugar
4 large eggs
3½ cups flour
2 teaspoons baking powder
½ teaspoon baking soda
¾ teaspoon ground nutmeg
¾ teaspoon ground cinnamon
½ teaspoon salt
½ cup milk
1 teaspoon vanilla
1 teaspoon maple flavoring
½ cup peeled and Granny Smith apple, cut into small dices
Streusel Topping
2 tablespoons cold unsalted butter, cut into pats
2 tablespoons dark brown sugar
3/4 cups chopped pecans
Bake Sweet Potatoes
To bake sweet potatoes, preheat oven to 400˚. Pierce each sweet potato several times with the tines of a fork and place on a rimmed baking sheet lined with foil. Bake until fork tender, about 45 minutes. Let the baked sweet potatoes cool to room temperature. Peel the skins off and mash the soft interior with a fork or potato masher. Measure out 2 cups. This may be covered and refrigerated overnight. If you want to bake your cake right away be careful to let the potatoes cool completely; if they are still warm when you mix the cake then they will melt the butterfat and make a heavy, messy cake.
Make The Topping
In a separate bowl combine the cold butter, brown sugar, and chopped pecans. Mix with a wooden spoon. This mixture will be crumbly. Place in the refrigerator to keep the butter mixture cold.
Make the Cake
Position a rack so the cake will sit in the middle of the oven and preheat the oven to 325˚. Line the bottom of your tube pan with parchment paper and spray the sides and bottom with baking spray.
Cut your softened butter into tablespoon-sized pats and cream with a mixer on medium speed for 1-2 minutes until the butter is smooth.
Combine the sugars in separate bowl. Gradually add to the creamed butter, ¼ cup at a time, beating at medium to high speed after each addition.
Add the eggs, one at a time, beating at medium to high speed for 1 minute after adding each one.
Reduce the mixer to low speed and add the mashed potatoes, ½ cup at a time.
Sift the flour into a separate bowl. Whisk the baking powder, baking soda, nutmeg, cinnamon, and salt into the flour.
Combine the milk, vanilla, and maple flavoring in a 2-cup liquid measure. With the mixer still on low speed, alternately add the flour mixture and milk mixture, beating after each addition. Start with a third of the flour mixture, beat, then add half of the milk mixture, beat again, and repeat until the last of the flour mixture has been added and beaten in.
Turn off the mixer, scrape down the sides of the bowl with a spatula, and give the cake batter a final stir making sure that all ingredients are mixed in.
Add the small diced apples, stirring until just incorporated.
Pour the batter into the prepared cake pan and use the back of a spoon to even out and smooth the batter.
Sprinkle the prepared streusel over the top of the cake.
Bake in the oven for 1 hour and 15 minutes before testing for done-ness. Then use a sharp knife or thin skewer to test the cake in a couple of places to determine whether it's finished. If the knife comes out clean then your cake is done. If it comes out with gooey cake stuck to it then bake cake for an additional 5 minutes and check again.
Cool in the pan for 20 -30 minutes. Then un-mold the cake by placing a cake plate over the top of the cake pan. Tip the cake onto the plate. At this point your cake will be upside down on your cake plate. To let it finish cooling right side up on a cooling rack, hold a cooling rack on the top of your cake and flip it onto a cake rack, topping side up.
Let cool completely before wrapping or cutting. Enjoy!