2 1/2 cups cake flour, sifted
1 1/3 cups sugar
1 tablespoon baking powder
1 teaspoon salt
1/2 cup vegetable oil
5 large eggs, separated
3/4 cup fresh orange juice
3 tablespoons orange zest
1/2 teaspoon cream of tartar
Lemon-Orange Buttercream Frosting
Garnishes: candied oranges and lemons, edible flowers, kumquat slices
How to Make It
Preheat oven to 350°. Combine first 4 ingredients in bowl of a heavy-duty electric stand mixer. Make a well in center of flour mixture; add oil, egg yolks, and orange juice. Beat at medium-high speed 3 to 4 minutes or until smooth. Stir in zest.
Beat egg whites and cream of tartar at medium-high speed until stiff peaks form. Gently fold into flour mixture. Spoon batter into 3 greased and floured 9-inch round cake pans.
Bake at 350° for 17 to 20 minutes or until a wooden pick inserted in center comes out clean. Cool in pans on wire racks 10 minutes; remove from pans to wire racks, and cool completely (about 1 hour).
Spread Lemon-Orange Buttercream Frosting between layers and on top and sides of cake.