Orange Ombre Cake

To prepare cake: Preheat oven to 325 degrees F. Coat three 8-inch cake pans with cooking spray and line the bottoms with parchment. Coat the parchment with cooking spray.

Whisk cake flour, whole-wheat flour, 1 cup granulated sugar, baking powder and salt in a medium bowl. Beat oil, orange juice concentrate, 1/4 cup water, 2 teaspoons orange zest, 1 teaspoon lemon zest and vanilla in the bowl of a stand mixer on low speed until well blended. On medium speed, gradually beat in egg yolks until thoroughly incorporated. Add the dry ingredients in 3 batches, beating on low just until smooth.

Beat egg whites in the stand mixer with the whisk attachment until foamy and opaque, about 1 minute. Add lemon juice and continue beating until soft peaks form, about 3 minutes. Gradually add the remaining 1/4 cup granulated sugar. Increase speed to high and continue to beat until stiff peaks form, 2 to 4 minutes more.

Gently fold one-third of the egg whites into the batter. Repeat with another one-third, folding until no white remains. Then thoroughly fold in the remaining whites, carefully reaching to the bottom of the bowl and lifting up to blend the batter with the whites until no streaks remain. Divide the batter equally among the prepared pans.

Bake until the tops are light brown and a toothpick inserted in the centers comes out clean, 20 to 25 minutes. Cool in the pans on wire racks for 5 minutes. Run a knife around the edges of the pans, then turn the layers out onto the wire racks to cool completely, about 30 minutes.

To prepare frosting: Combine goldenberry powder and 2 tablespoons warm water to create a paste. Beat cream cheese, confectioners' sugar, orange zest and lemon zest with an electric mixer until fluffy, about 2 minutes. Transfer 1 cup of the frosting to a small bowl. Transfer 1/2 cup to another small bowl and stir in 1 1/2 teaspoons of the goldenberry paste. Transfer 1/2 cup frosting to another small bowl and stir in 1 tablespoon of the goldenberry paste. Stir the remaining 3 tablespoons goldenberry paste into the remaining 1/2 cup frosting.

Place one layer on a cake stand or plate. Spread 2 tablespoons of dark orange frosting on top to within 1/4 inch of the edge. Top with a second cake layer. Spread 2 tablespoons of medium orange frosting on top to within 1/4 inch of edge. Top with the third cake layer. Spread half of the white frosting over the whole cake. Place the cake in the freezer while you prepare the piping bags.

Transfer the three colored frostings to small piping bags (or sealable plastic bags with a corner snipped off). Starting with the bottom layer, pipe a band of dark orange frosting a third of the way up the cake. Then pipe a medium orange band of frosting around the middle of the cake. Pipe the light orange frosting around the sides of the top layer. Spread the remaining white frosting over the top of the cake. Dip a large icing spatula or knife in hot water and use it to spread and smooth the frosting on the sides while rotating the cake. Dip again and smooth the frosting on top of the cake.