This Purple Sweet Potato Cake is bright and vibrant both in color and flavor! A whipped tofu cream cheese filling and a purple frosting make for a unique cake!
To make a Purple Sweet Potato Cake has always been on my bucket list.
But let’s clear things up, there are different types of purple sweet potatoes. Why is this important? Using different purple sweet potatoes will yield different colors, textures, and moisture contents.
To name three there are Stokes Purple Sweet Potatoes, Okinawan Sweet Potatoes, and Ube Sweet Potatoes. You may think that these three can be interchanged, but they cannot.
Stokes sweet potatoes originate from North Carolina. They have a purple skin and equally purple flesh that is both dry and dense. The violet color intensifies when baked or cooked. Okinawan Sweet Potatoes—sometimes called Hawaiian Sweet Potatoes—have a pale brown skin and lavender purple colored flesh. They are creamier than Stokes and, when baked, they have a soft purple-blue color. Finally ube is tricky and it not easily available in the United States. Its thick, brown bark-like skin encases a lilac-white flesh. Since ube is laborious to cook and break down than most sweet potatoes, there are many processed ube items (think jams, powders, purees, etc).
Based on my geographical location and limited access, I worked with the Stokes variety. Not only was access apart of my decision, but moisture and color were important. A drier texture helps with controlling moisture. Better yet, Stokes have a brighter purple color, meaning I wouldn’t have to use as much food dye.
Traditionally, fat and sugar a creamed together, but for this Purple Sweet Potato Cake, I did something different. Beating the mashed purple sweet potatoes with the sugar yields a smooth batter, lump free batter. You may think chunks of sweet potato would be okay, but the lumps and chunks created an off putting texture. You do not want lumpy chunks of purple sweet potato floating around in this cake. Another tip is to add the food gel into the wet ingredients. Beating the food gel in the beginning does two things: assures even distribution of color and it prevents gluten formation in the batter (in terms of putting gel at the end where you’d be over beating the batter to distribute the food gel’s color).
The whipped tofu filling has a mousse-like texture. Its neutral vanilla-laced flavor allows the purple sweet potato to shine.
Purple on purple on purple, make for a striking appearance, driving home the star ingredient of purple sweet potato. Equally purple sprinkles drive home the hue in this Purple Sweet Potato Cake!
- 2 ¾ cups all-purpose flour
- 2 teaspoons baking powder
- 1 teaspoon baking soda
- ½ teaspoon fine salt
- 1 ½ cups granulated sugar
- 1 cup cooked mashed purple sweet potato, preferably Stokes Variety
- Purple food gel
- 1⁄3 cup canola oil
- 2 large eggs, room temperature
- 1 cup buttermilk, room temperature
- ½ cup sour cream, room temperature
- 2 teaspoons vanilla extract
- 1 ½ cups heavy cream
- 1 teaspoon vanilla extract
- 2 teaspoons granulated sugar
- ½ cup (1 stick, 4 ounces) unsalted butter, room temperature
- 2 cups powdered sugar
- ⅛ teaspoon fine salt
- 2 teaspoons vanilla extract
- 8 ounces tofu cream cheese, room temperature
- 1 cup (2 sticks, 8 ounces) unsalted butter, room temperature
- 8 ounces cream cheese, room temperature
- 6 to 8 cups powdered sugar
- ¼ teaspoon fine salt
- 1 tablespoon vanilla extract
- Purple food gel
- ¼ cup heavy cream
- White Frosting
- Purple Sprinkles
- Preheat oven to 350 degrees F. Grease three 8-inch cake pans with baking spray, set aside.
- Whisk flour, baking powder, baking soda, and salt together, set aside. Beat sugar, mashed purple sweet potato, and purple food gel until smooth and lump free, about 4 minutes on medium speed. Scrap bowl and paddle as needed. Add oil, continuing to beat until combined. Beat eggs in one at a time. In a spouted measuring cup, whisk together buttermilk, sour cream, and vanilla.
- With mixer on low add dry-ingredients in 3 additions alternately with wet-ingredients in 2 additions, beginning and ending with dry-ingredients. Give batter a few stirs by hand to ensure even incorporation.
- Divide between prepared pans and bake for 20 to 26 minutes, rotating halfway. The cakes will begin to pull away from the pans and a toothpick inserted will come out with a few moist, not wet, crumbs. Let cakes cool in pans for 5 minutes. Invert onto a wire rack to cool completely. If making ahead of time, wrap in plastic wrap and refrigerate until you're ready to assemble.
- Whip heavy cream in a stand mixer fitted with a paddle attachment. Once medium peaks form, add vanilla and granulated sugar until medium-stiff peaks form, transfer into another bowl.
- Fit stand mixer with a paddle attachment. Beat butter until smooth, about 1 to 2 minutes on high, scrap sides and bottom of bowl down. Add powdered sugar and beat until smooth and lump free, beat in salt and vanilla. With mixer of low, add tofu cream cheese, beating until just combined. Once tofu cream cheese is incorporated, don't over beat filling. Fold in whipped cream by hand. Refrigerate until ready to assemble.
- Cube butter and cream cheese, and add into a stand mixer fitted with a paddle attachment. Beat at medium-high speed until smooth and lump free, about 3 minutes. Scraping the bowl and paddle as needed. Gradually add powdered sugar followed by salt, vanilla, vanilla, and food gel. Raise speed to medium-high and beat until aerated, another 3 minutes. Add heavy cream as needed, a few teaspoons at a time, to achieve the right consistency.
- Apply a bit of frosting onto a cake board and secure the first cake layer. Pipe a boarder of white frosting around perimeter, fill center with Whipped Tofu Filling. Stack second cake layer on, repeat frosting and filling process and top with the final third layer. Lightly apply a dirty layer of purple frosting. Refrigerate for 15 minutes, apply a thicker layer of purple frosting. Apply sprinkles and pipe with remaining white frosting.
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