Ingredients
The Cake
- 3 large egg whites, at room temperature (1/4 cup plus 2 tablespoons/3.2 ounces/90 grams)
- Red food color (see notes below), 1 bottle (2 tablespoons/1 ounce/30 grams)
- Pure vanilla extract (1 1/2 teaspoons/1 1/2 teaspoons/1 1/2 teaspoons)
- Cake flour or bleached all-purpose flour, sifted (2 cups/7 ounces/200 grams)
- Superfine sugar (1 cup/7 ounces/200 grams)
- Baking powder (3 teaspoons/3 teaspoons/3 teaspoons)
- Unsweetened cocoa powder (1 teaspoon/1 teaspoon/1 teaspoon)
- Salt (1/2 teaspoon/1/2 teaspoon/1/2 teaspoon)
- Canola or safflower oil, at room temperature (1/4 cup/2 ounces/58 grams)
- Unsalted butter, kept 65°to 75°F, or 19° to 23°C (4 tablespoons/2 ounces/57 grams)
- Low-fat buttermilk (1/2 cup/4.2 ounces/121 grams)
- One 9 by 2-inch heart-shape or round cake pan (8 to 8²⁄³ cups), encircled with a cake strip, bottom coated with shortening, topped with parchment cut to shape, then coated with baking spray with flour.
The Frosting
- White chocolate containing cocoa butter (3 ounces/85 grams)
- Cream cheese, softened but still cool (4 ounces/113 grams)
- Unsalted butter, softened but still cool (2 tablespoons/1 ounce/28 grams)
- Crème fraîche or sour cream (1/2 tablespoon/0.2 ounces/7 grams)
- Almond extract (1/8 teaspoon/1/8 teaspoon/1/8 teaspoon)
Method
The Cake
- Twenty minutes or more before baking, set an oven rack in the lower third of the oven and preheat the oven to 350°F/175°C.
- Prepare pan
- In a medium bowl, whisk the egg whites, red food color, and vanilla just until lightly combined. (Caution: Be careful with the red food color: it stains effectively, but also unmercifully.)
- In a medium bowl, whisk together the flour, sugar, baking powder, cocoa, and salt.
- In the bowl of a stand mixer fitted with the flat beater, mix the oil and butter on medium speed for 1 minute. It will not be completely smooth. Add the flour mixture and buttermilk. Mix on low speed until the dry ingredients are moistened. Raise the speed to medium and beat for 1½ minutes. Scrape down the sides of the bowl. Starting on medium-low speed, gradually add the egg mixture to the batter in two parts, beating on medium speed for 30 seconds after each addition to incorporate the ingredients and strengthen the structure. Using a silicone spatula, scrape the batter into the prepared pan and smooth the surface evenly with a small offset spatula.
- Bake for 25 to 35 minutes, or until the wire cake tester inserted in the center comes out clean and the cake springs back when pressed lightly in the center. The cake should start to shrink from the sides of the pan only after removal from the oven.
- Let the cake cool in the pan on a wire rack for 10 minutes. Run a small metal spatula between the sides of the pan and the cake, pressing firmly against the pan, and invert the cake onto a wire rack that has been coated lightly with nonstick cooking spray. To prevent splitting, reinvert the cake so that the top side is up. Cool completely.
The Frosting
- Heat the chocolate until almost completely melted. Use a small microwavable bowl, stirring with a silicone spatula every 15 seconds (or use the top of a double boiler set over hot, not simmering, water, stirring often—do not let the bottom of the container touch the water).
- Remove the white chocolate from the heat and, with the silicone spatula, stir until fully melted. Allow it to cool until it is no longer warm to the touch but is still fluid.
- In a food processor, process the cream cheese, butter, and crème fraîche for a few seconds until smooth and creamy. Scrape down the sides.
- Add the cooled melted white chocolate and pulse it in a few times until it is smoothly incorporated. Add the almond extract and pulse it in.
Use white chocolate containing cocoa butter, such as Green & Black’s with vanilla seeds or Valrhona. The frosting becomes more firm in the refrigerator. For a whiter frosting without the subtle flavor of the white chocolate, you can replace the white chocolate with 1 cup (lightly spooned into the cup)/4 ounces/115 grams powdered sugar and ¼ teaspoon vanilla extract.
When the cake is completely cool, set it on a serving plate. Frost the top with swirls of buttercream.
Notes
Some people have a problem with the idea of using red food color and use beet juice in its place. In recipes using baking soda, the beet juice would turn brown, but with this highly acidic batter, the crumb will stay red, though not as pretty a red as offered by the food color. The best way to harvest beet juice is to roast the well-washed beets in their skins, leaving an inch of root and stems, in an aluminum foil package at 350º/175ºC for about 45 minutes for medium beets, up to about 1 hour and 15 minutes for large ones. Remove the beets and use the foil to pour the beet juice into a small container.
For a distinct chocolate flavor, you can use up to ¼ cup cocoa/0.7 ounce/21 grams, sifted before measuring, but decrease the flour by the same amount. The color will be a much darker red.