Serves 8–10 | Start to finish: 1 hour and 15 minutes (active time 30 minutes)
One of the greatest joys of high summer in Seattle is the triumphal seasonal progress of stone fruits through the farmers’ markets. I used early plums for this month’s spectacular ice cream cake, but the classic chocolate-hazelnut combination would marry equally well with whichever stone fruit is currently fresh and ripe in the market, from cherries and apricots to all manner of plums, peaches, and nectarines.
This cake is not difficult, but it does take a little time to create, though your efforts will be rewarded with star billing at your next potluck or celebration. If you want to speed things up by substituting a good commercial ice cream for the middle layer, or by just serving the base cake with a scoop of ice cream and some pureed fruit or a drizzle of good olive oil and a sprinkling of sea salt, well, we won’t be telling.
For the chocolate-hazelnut cake layer:
1/2 cup hazelnut flour (or almond flour, if you prefer)
2 tablespoons all-purpose flour
1/2 teaspoon baking powder
1/2 teaspoon baking soda
1/4 cup demerara or turbinado sugar (or granulated, if you prefer)
6 ounces bittersweet chocolate chips or wafers
1/2 cup olive oil
1/8 teaspoon sea or kosher salt
4 large eggs, divided and at room temperature
1/2 cup granulated sugar
1/8 teaspoon cream of tartar or 1/2 teaspoon lemon juice or white wine vinegar
Preheat oven to 375°F.
Grease the bottom and sides of an 8×3-inch springform cake pan with olive oil and line the bottom with a circle of parchment paper.
Place the hazelnut flour, all-purpose flour, baking powder, baking soda, and demerara or turbinado sugar in a bowl and stir thoroughly to combine.
Place the chocolate chips, olive oil, and salt in a double boiler or a metal bowl set over a pan of barely simmering water. Stir until the chocolate has melted, taking care that the water does not get too hot. Set aside to cool for about five minutes.
Whisk the egg yolks and the granulated sugar together, then whisk into the melted chocolate mixture until smooth and combined.
Using an electric whisk and a clean metal bowl, beat the egg whites and either the cream of tartar, lemon juice, or vinegar until stiff peaks form and the beaters leave deep trails. Take care not to over beat.
Using a rubber spatula, gently fold a third of the egg whites into the chocolate mix, then fold in a third of the hazelnut mix, being careful to retain as much air in the batter as possible. Alternate folding the remaining two thirds of the egg whites and hazelnut mix into the batter until all the ingredients are fully incorporated.
Pour the batter—it should resemble a light, pourable mousse—into the prepared cake pan, set it on a baking tray, and bake in the oven 35–45 minutes until it is set, and a skewer or stick of spaghetti inserted into the center comes out with moist crumbs. Set the pan on a rack to cool. You should expect the cake to sink a little. Do not remove it from the pan until cool.
For the ice cream:
Active time: about 25 minutes
Cooling and freezing time: according to your ice cream maker
1 pound plums or other stone fruit in season
2 cups half and half
3/4 cup sugar
3 egg yolks
1/2 teaspoon vanilla extract
1/2 teaspoon kirsch or vodka
Cut the plums or other fruits in half and remove the pits (keep the pits if you’re using cherries). Put the fruit in a saucepan with half a cup of water and cook over medium heat for about 15 minutes until very soft. Remove from the heat and push the puree through a fine sieve to remove tough skins and pits. Allow to cool.
Put a large bowl of cold water to one side, close to where you will make the custard. In a heavy saucepan, gently heat the half and half with the sugar until the sugar has dissolved. Whisk the egg yolks in a separate bowl. Add half a cup of the warm half and half mixture and whisk it into the eggs.
Return the egg mixture to the warm cream in the saucepan and cook it over low heat, stirring constantly, until it bubbles round the edges and starts to thicken, coating the back of the spoon. Immediately plunge the pan into the bowl of cold water to prevent curdling (if your custard does curdle a little, just push it through a sieve and it should be fine, just a little less smooth).
Cool the custard and add 1 cup of the fruit puree, the vanilla extract, and the kirsch or vodka (this latter enhances texture). Chill in the fridge and then churn according to the directions on your ice cream maker.
For the no-churn, whipped topping:
Active time: about 10 minutes + freezing time
14-ounce can of sweetened condensed milk
1 teaspoon kirsch or vodka
2 cups heavy cream
1/4 cup grated chocolate or cocoa nibs
Pour the condensed milk into a large bowl and stir in the kirsch or vodka.
In a separate bowl, whip the heavy cream into stiff peaks and gently fold into the condensed milk.
Use this mix for the final layer of your cake (see assembly instructions below).
To assemble the cake:
When the cake layer is fully cooled, remove the sides of the springform pan and slice the sunken top off the cake with a serrated knife to create a level base for the ice cream. You will end up removing about a third of the cake. Roughly crumble the removed pieces of cake into a bowl and set the crumbs aside.
Take a long strip of parchment paper about 6 inches wide (3 inches wider than the pan is high) and curl it around the cooled cake (which should still be sitting on the base of the pan). Clean and re-oil the side ring of the pan, carefully lower it over the paper and cake, and reform the pan. You should end up with the cake in the bottom and the sides lined with a strip of parchment paper extending above the top edge.
Make the ice cream and, when it is churned, spread it over the bottom layer of cake. Cover the ice cream layer with the leftover cake crumbs and then place in the freezer. Make the no-churn whipped ice cream topping, spread it over the cake crumb layer, and freeze overnight.
10 minutes before serving, remove the springform sides, carefully peel off the parchment paper, and slide the cake off the pan bottom. Decorate the cake with grated chocolate or cacao nibs.
