Conversation Heart Cakes
Author: 
Yield: 6 4-inch (10-cm) individual heart-shaped cakes
 
Ingredients
For the Black Velvet Cake
  • 2 tablespoons unsweetened dark cocoa powder, such as Valrhona
  • 2 tablespoons unsweetened black cocoa powder (see Baked Note)
  • ¼ cup (60 ml) boiling water
  • 1 tablespoon black food gel (optional)
  • 2½ cups (315 g) cake flour (not self-rising)
  • 1 teaspoon kosher salt
  • 3 ounces (¾ stick/85 g) unsalted butter, softened, plus more for the pan
  • 1 tablespoon plus 1½ teaspoons vegetable shortening, at room temperature
  • 1 2⁄3 cups (330 g) granulated sugar
  • 3 large eggs
  • 1 cup (240 ml) well-shaken buttermilk
  • 1 teaspoon pure vanilla extract
  • 1 tablespoon cider vinegar
  • 1 teaspoon baking soda
For the Vanilla Cream Cheese Frosting
  • 3 cups (340 g) confectioners’ sugar
  • 8 ounces (2 sticks/225 g) unsalted butter, softened
  • 2 (8-ounce/226-g) packages cream cheese, softened
  • 1 tablespoon plus 1 teaspoon pure vanilla extract
  • ½ teaspoon kosher salt
  • Food dye or gel (optional)
For the Assembly
  • 4 ounces (115 g) white chocolate, chopped
  • Food dye or gel (optional)
Instructions
Make the Black Velvet Cake
  1. Preheat the oven to 325°F (165°C) and position a rack in the center of the oven. Butter an 18-by-13-inch (46-by-33-cm) rimmed baking sheet, line with parchment paper, butter the parchment, and set aside.
  2. In a medium bowl, whisk together both cocoa powders, the water, and food gel, if using. Set aside to cool.
  3. In another bowl, sift together the cake flour and salt.
  4. In the bowl of a standing mixer fitted with the paddle attachment, beat the butter and shortening together on medium speed until light and smooth, about 5 minutes; the mixture will appear to string or ribbon throughout the bowl. Add the sugar and beat on medium speed until the mixture appears light and fluffy, about 5 minutes. Add the eggs, one at a time, beating well after each addition. Scrape down the sides and bottom of the bowl.
  5. Stir the buttermilk and vanilla into the cocoa mixture.
  6. Add the flour mixture to the mixer bowl in three parts, alternating with the cocoa mixture, and beginning and ending with the flour mixture. Scrape down the sides and bottom of the bowl and mix again for 10 seconds. In a small bowl, mix together the vinegar and baking soda until the baking soda dissolves; the mixture will fizz. Add to the batter and mix until just combined.
  7. Pour the batter onto the prepared baking sheet, smoothing the top. Bake the cake, rotating the pan after 10 minutes, until a cake tester inserted into the center of the cake comes out clean, 20 to 30 minutes.
  8. Cool the cake completely in the pan on a wire rack. If possible, place the pan and cooled cake in the freezer for another 45 minutes. (A chilled cake will often produce better, cleaner results when cutting out the shapes, though this step is not necessary.)
  9. Line another baking sheet with clean parchment.
  10. Use a 4-inch (10-cm) heart-shaped cookie cutter to cut out 12 cake hearts; cut them out as closely as possible to get 12 hearts out of the layer cake. Place the hearts on the clean parchment and place in the freezer while you make the frosting.
Make the Vanilla Cream Cheese Frosting
  1. Sift the confectioners’ sugar into a large bowl and set aside.
  2. In the bowl of a standing mixer fitted with the paddle attachment, beat the butter until it is completely smooth. Add the cream cheese and beat until combined.
  3. Add the confectioners’ sugar, vanilla, and salt and beat until smooth. Be careful not to overbeat the filling, or it will lose structure. Add the food dye, if using, drop by drop and beat until the desired color is reached. Chill the frosting in the refrigerator for about 5 minutes so it is easier to work with.
Assemble the Conversation Heart Cakes
  1. Cut parchment into six squares, each slightly larger than the hearts, and place them on a baking sheet. Place the first cake heart on a parchment, spread a thin layer of frosting over just the top, and top with another heart, bottom side up. Using a small offset spatula, cover the entire heart cake with a thin layer of frosting (a crumb coat). Continue this process, making 6 two-layer cakes in total, then transfer the baking sheet with all of the crumb-coated cakes to the refrigerator to set, 5 to 10 minutes.
  2. Remove all of the cakes from the refrigerator. Cover the heart cakes with a generous layer of frosting, slightly more than ½ cup (130 g) each, and use the offset spatula to accentuate the heart shape (i.e., make sure the sides and tops are flat so that they resemble the candy conversation hearts). Refrigerate all of the cakes to set, about 5 minutes.
  3. Place the white chocolate in a microwave-proof bowl and heat on medium power for 10 seconds. Remove and stir the chocolate. Repeat this process until it is just melted. Stir in the food dye, if using. Scrape the warm mixture into a pastry bag fitted with the smallest plain round tip. The chocolate should be warm enough to write with, but not so warm that it oozes out.
  4. Remove the cakes from the refrigerator. Working quickly, write your messages on the cakes. Refrigerate the cakes one more time to set, about 5 minutes.
  5. Take the cakes from the refrigerator, gently remove the parchment from underneath each cake, transfer each to a clean serving plate, and serve to your sweetheart(s). (The frosting can also be made 24 hours ahead; cover the bowl tightly and refrigerate, letting the frosting soften at room temperature before using.)
Notes
How to store: The cakes can be stored, tightly covered, in the refrigerator for up to 2 days. Bring to room temperature before serving.
Recipe by Baked Sunday Mornings at http://bakedsundaymornings.com/2016/02/02/in-the-oven-conversation-heart-cakes/