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purple sweet potato magic cake slice

(Ube)Purple Sweet Potato Magic Cake

Kathleen Royal Phillips
Purple Sweet Potato Magic Cake is a version of Purple Velvet Magic Cake in my cookbook, Magic Cakes. The Purple Velvet Magic Cake in my cookbook is made with ube powder (made from purple yams from Philippines) and Purple Sweet Potato Magic Cake is made with fresh purple sweet potatoes (from California). The taste is similar but the color from the sweet potatoes is more vibrant than the ube powder and didn't need any food coloring.
Prep Time 15 mins
Cook Time 38 mins
Cool and chill 3 hrs
Total Time 53 mins
Course Dessert
Cuisine American
Servings 8 servings


  • springform pan


  • 1 medium purple sweet potato
  • 4 large eggs at room temperature
  • 3/4 cup granulated sugar
  • 1/2 cup 1 stick salted butter, melted
  • 1 teaspoon vanilla extract
  • 2/3 cup all-purpose flour
  • 2 cups lukewarm whole milk
  • 1/2 teaspoon cream of tartar
  • 2 cups whipping cream
  • 1 tablespoon sugar


  • Preheat the oven to 400°F. Place sweet potato on a foil lined pan. Bake for 45 minutes or until tender when tested with a fork. Let it cool to room temperature. Remove the peel and mash the sweet potato. You should have 3/4 cup potato puree.
    Coat an 8-inch springform pan with baking spray or line an 8-inch cake pan with aluminum foil or parchment paper, if desired, and coat with baking spray.
  • Reduce oven to 325 degrees.
  • Separate the eggs; place the egg yolks in a mixing bowl with the sugar and beat on high speed with an electric mixer for 2 minutes, or until lemon-colored. On low speed, gradually add the melted butter, mashed sweet potato, and vanilla, scraping down the sides as needed. Add the flour and mix just until flour is combined. Gradually add the milk, beating just until combined. 
  • If using the same mixer and beaters to beat the egg whites, wash the beaters thoroughly; place the egg whites in a separate mixing bowl. Beat on medium speed until foamy; add the cream of tartar. Increase the speed to high and beat until the egg whites form stiff peaks, about 2 minutes. Gently whisk about one-third of the egg whites into the thin batter; gently fold the remaining egg whites in with a silicone spatula. Pour the batter in the prepared cake pan. Bake at 325 degrees for 38 minutes, or until the center jiggles slightly when gently shaken.
  • Let cool completely on a wire rack, about 1 hour. Cover and refrigerate at least 2 hours to chill. Remove sides and bottom of springform pan and transfer cake to a serving plate.
  • Beat whipping cream and 1 tablespoon sugar in a mixing bowl at medium-high speed until stiff peaks form; spread it on top of cake. Garnish with edible flowers such as Oxalis or shamrock blooms.


Regular sweet potatoes can be used for this recipe to make a perfect Fall cake. Add 1/2 teaspoon pumpkin pie spice to the flour mixture for a sweet potato pie flavored-cake.
You can also cook the sweet potato in the air fryer for about 40 minutes depending on the size of your potato. Make sure it is very tender.
Hydrated ube powder can also be substituted.
Keyword magic cake, sweet potato, ube