The light texture of this unusual cake will surprise you. It’s made with potatoes.
- 2 vanilla beans, divided
- 1½ cup water
- .75 cup sugar, plus extra for topping, divided
- 8 pitted dates, each cut into 8 slivers
- 1¼ cup plus, 2 tablespoons heavy cream, plus more if necessary
- 1 tablespoon chicory
- ⅓ cup coffee beans, crushed
- 5½ ounce milk chocolate, chopped
- 1 pound idaho potatoes
- 2 tablespoon all purpose flour
- ½ teaspoon baking powder
- 2 large eggs, separated
- 3½ tablespoon unsalted butter, melted
- 1 large egg yolk
- ¼ cup slivered almonds
Prepare the syrup: Cut one vanilla bean lengthwise in half and, using the back of a knife, scrape the pulp out of the pod. Bring the water, ¼ cup sugar, and vanilla bean pod and pulp to a boil in a small saucepan. As soon as the syrup comes to a boil, pull the pan from the heat, stir in the dates, and set aside to cool.
Prepare the cream: Put the cream, the chicory, and coffee beans in a medium saucepan and bring to a boil. Pull pan from the heat, cover and set the cream aside to infuse for 15 minutes. Meanwhile, place the chocolate in a metal bowl and set out a glass measuring cup.
Strain the infused cream into the measuring cup and, if it doesn’t come up to the 1‑cup mark, add enough additional cream to make an even cup. wash and dry Saucepan, pour in the infused cream and bring it back to a boil. Add the hot cream to the chocolate in two additions, each time very gently whisking the cream into the chocolate. You don’t want to beat air into the mixture, nor do you want to overcook it, so go slowly and easily. When the cream in homogenous, press a piece of plastic wrap against the surface to create an airtight seal and chill. Before serving whisk the cream until firm enough to form rounded spoonfuls.
Prepare the cake: Peel the potatoes, cut them into quarters, and toss them into a pot of cold salted water. Bring to a boil and cook until the potatoes can be pierced easily with a knife. Drain the potatoes, then put them back into the pot and, shaking the pot constantly over medium heat, heat the potatoes just enough to cook off the extra moisture. Puree the hot potatoes through a food mill or potato rices and cool them to room temperature. Reserve 1 (packed) cup of potato puree. Use the rest for something else.
Center a rack in the oven and preheat oven to 400 degrees F. Butter and 8- by 2‑inch round cake pan, dust it with flour, tap out the excess, and place the pan on a baking sheet.
Whisk together the flour, baking powder and 2 tablespoons of the remaining ½ cup sugar and set aside.
Cut the remaining vanilla bean lengthwise in half and, using the back of a knife, scrape the pulp out of the pod. Working in a mixer fitted with a whisk attachment, beat the egg whites with the vanilla bean pulp on medium-low speed until they are frothy and start to come together, about 2 minutes. Increase the speed to medium-high and, when the whites form very soft peaks, start adding 6 tablespoons of sugar in a slow, steady stream. Continue to beat until the whites are firm but still glossy. Set aside.
In a large bowl, whisk together the cooled reserved 1‑cup of mashed potatoes, the butter, the remaining 2 tablespoons cream, and egg yolks until smooth. Switch to a rubber sptchula and gently but thoroughly stir the flour mixture into the potatoes. Finally, delicately fold in the beaten egg whites.
Fill the prepared pan with the batter, gently smoothing the top. Sprinkle the top with the almond slivers and about 1 tablespoon sugar. Slide the baking into the oven and bake for 20 to 25 minutes, rotating the sheet front to back at the 10 minute mark. When baked, the cake should be golden brown, just pulling away from the sides of the pan, and springy to the touch.
Run a small blunt knife between the cake and the sides of the pan and unmold the cake onto a cooling rack. Invert the cake bring the topside back up and cool to room temperature on the rack.
To serve: Cut the cake into 8 wedges and place one on the center of eight separate plates. Arrange some date slivers on the plate on one side and garnish each with a scoop of chicory cream. Drizzle the vanilla syrup around the cake and serve.