Milk Street Recipe: Chocolate, Prune and Rum Cake

From Episode 102, The New Baking

In this episode, host Christopher Kimball goes to London’s Violet Bakery to visit with rising pastry star Claire Ptak. After picking up some of her techniques, he returns to the kitchen and works with Milk Street cook Matthew Card to make this Chocolate, Prune and Rum Cake.

Start to finish: 1 hour and 20 minutes (30 minutes active), plus cooling Servings: 12

INGREDIENTS

• 9 tablespoons salted butter (1 tablespoon softened)
• 8 ounces pitted prunes (about 1½ cups), finely chopped
• ⅓ cup dark rum
• 1 tablespoon molasses
• 12 ounces bittersweet chocolate, finely chopped
• 6 large eggs, separated
• ⅓ cup plus ¼ cup white sugar
• ½ teaspoon kosher salt

INSTRUCTIONS

1. Heat the oven to 325°F with a rack in the middle position. Coat the bottom and sides of a 9-inch springform pan evenly with the tablespoon of softened butter.
2. In a 2-cup liquid measuring cup, combine the prunes, rum and molasses. Microwave until the rum is bubbling, 45 to 60 seconds. Let sit for 15 minutes, stirring occasionally.
3. In a medium saucepan over medium heat, melt the remaining 8 tablespoons of butter. Remove from the heat and immediately add the chocolate, then whisk until melted and completely smooth. In a large bowl, whisk together the egg yolks and ⅓ cup of sugar until pale and glossy, about 30 seconds. Slowly add the melted chocolate mixture and continue whisking until smooth. Stir in the prune mixture.
4. Using a stand mixer with a whisk attachment, whip the egg whites and salt on medium-high speed until light and foamy, about 1 minute. With the mixer running, slowly sprinkle in the remaining ¼ cup of sugar and continue to whip until the whites are thick and glossy and hold soft peaks, about 1 minute.
5. Whisk ⅓ of the whipped egg whites into the chocolate mixture to lighten it. Gently fold in the remaining whites with a rubber spatula until the batter is marbled but not fully blended.
6. Pour the batter into the prepared pan. If needed, smooth the top with a spatula. Bake until the edges of the cake are firm and cracked, 35 to 40 minutes. The center will be just set, yet soft to the touch. Cool the cake in the pan on a wire rack for at least 1 hour before serving (the cake will settle and sink as it cools).
7. Don’t over-bake this cake. Don’t be alarmed if the center still jiggles a bit and yields to gentle pressure; the cake will continue to set after it comes out of the oven.

Recipe courtesy of WGBH.