- 2 3/ 4 cups cake flour, sifted
- 1 3/ 4 cups granulated sugar
- 1 1/ 4 teaspoons baking soda
- 1 1/ 4 teaspoons baking powder
- 1 teaspoon coarse kosher salt
- 2 large eggs
- 2 large egg whites
- 1 1/ 2 cups whole buttermilk
- 3/ 4 cup vegetable oil
- 1 teaspoon vanilla extract
- 1 teaspoon orange extract
- 8 ounce can mandarin oranges, (in juice, not syrup)
- 8 ounces strawberries, washed, hulled and chopped
- 2 tablespoons granulated sugar
- 1 tablespoon water
- 1/ 2 teaspoon lemon juice
- 2 cups unsalted butter, unsalted, softened to room temperature
- 4 cups powdered sugar
- 1 tablespoon meringue powder
- 1/ 4 teaspoon coarse kosher salt
- 2 tablespoons milk or cream, if needed
If you don't have buttermilk, pour 1 tablespoon white distilled vinegar into a measuring cup and then add whole milk up to the 1 1/2 cup line. Microwave on high for one minute to curdle the milk. You can also swap 1/2 cup orange juice for the same amount of milk/buttermilk for more orange flavor in your cake. I used the orange juice that I drained from the canned Mandarin oranges.
You might wonder why I used canned oranges instead of fresh, and it's really just because fresh oranges can have a tough, pithy skin that's undesirable in baked goods. Canned Mandarin oranges are soft and juicy, and work really well in this recipe.
To make the heart shape, you'll need two 6-inch square pans and two 6-inch round pans to make a two-layer heart cake that's about 9 inches in diameter and 5 inches tall once assembled. (If you like, you could make a one-layer heart cake by baking the batter in one 8 or 9-inch square pan and one 8 or 9-inch round pan, but the assembled cake will be much larger in diameter and will need to be frosted on a large baking sheet or serving platter. Using the smaller cake pans keeps the assembled cake a more standard sized-layer cake.) After the cakes are cooled, you'll make the heart by cutting the round cakes in half right down the center. Arrange the half circles of cake against two sides of the square cake (joining them together with a little buttercream), and you'll have a heart.
Before frosting the baked cakes, I've also pricked them with a toothpick and brushed them with a small amount of Cointreau or orange-flavored liqueur. This is optional, but really delicious. You could also add a little orange marmalade in between the layers.
Preheat the oven to 350. Grease two 6-inch square pans and two 6-inch round pans with non-stick spray.
In the bowl of your stand mixer fitted with a paddle attachment, combine the flour, sugar, baking soda, baking powder and salt.
In a separate bowl, whisk together the eggs, egg whites, buttermilk, oil, vanilla and orange extracts. Drain the oranges (see note above about substituting the drained orange juice for some of the buttermilk). Roughly chop the oranges and add to the wet ingredients.
Add the wet ingredients to the dry, and mix on low to combine, then on medium for two minutes until mostly smooth. Divide the batter between the pans. (You should put slightly more batter in the square pans, which have greater volume, to keep all your baked cakes the same height.)
Bake until a toothpick comes out clean, about 30 minutes. Cool the cakes in the pans completely.
Buttercream and Assembly
In a saucepan, combine the strawberries, granulated sugar, water and lemon juice. Bring to a boil, then reduce to a simmer. Cook, stirring occasionally, until thick and jammy, and reduced to about 1/2 cup. Cool completely and puree.
In the bowl of your stand mixer fitted with the whisk attachment, beat the butter with the (completely cooled) strawberry reduction for one minute. With the mixer on low, add the powdered sugar, meringue powder and salt. Increase the speed to medium and whip for 4-5 minutes, scraping the bowl occasionally, until very light and fluffy. Add the milk, only if needed, to thin the buttercream a little for desired consistency.
Remove the cooled cakes from the pans. Keep the square cakes whole, but cut the round cakes right down the middle, so that you have two squares and four half-circles.
Place one square cake on a large cake pedestal, and arrange two half-circles on two sides of the square to form a heart. Use a little buttercream on the cut edge of the half-circles to secure them to the square cake. Frost with a layer of buttercream on top, and then arrange the second square and half-circles on top to form a two-layer heart cake.
Frost all over with a thin crumb coat of buttercream, then chill for 30 minutes. Frost with a final layer of buttercream.
Garnish the cake with fresh strawberries and fresh or canned orange slices.