To really turn this cake into a stellar dessert, serve it with Roasted Pears with Caramel Sauce.
5 oz. (1 cup) whole almonds
5 oz. (10 Tbs.) unsalted butter;
more for the pan
1-1/2 cups granulated sugar
3-3/4 oz. (1 cup) cake flour
2 tsp. baking powder
Pinch table salt
2 Tbs. dark rum
1 tsp. pure vanilla extract
1/4 cup sour cream
9 large egg whites, ideally at room temperature
1/4 cup sliced almonds
Confectioners’ sugar for dusting (optional)
Heat the oven to 350°F. Butter a 10-inch springform pan and line the bottom with a round of parchment or waxed paper.
Spread the whole almonds on a baking sheet and heat them in-the oven, shaking the pan every couple of minutes, until lightly toasted and aromatic, 5 to 9 minutes.
In a food processor, pulse the whole almonds and 3/4 cup of the sugar until finely ground. Pour the mixture into a medium bowl and stir in the cake flour, baking powder, and salt. Set aside.
Stir the rum, vanilla extract, and sour cream into the browned butter.
Using a stand mixer or a hand mixer, beat the egg whites in a large, clean, dry bowl, beginning on low speed until they start to foam. Increase the speed to medium high and beat until the whites barely hold peaks. Beat in the remaining 3/4 cup sugar in a very slow, steady stream; continue beating the whites until they hold soft peaks.
Scoop a large dollop of the egg whites into the butter mixture and stir it in. Gently fold half of the almond mixture into the remaining egg whites and then half of the butter mixture into the egg whites. Repeat, ending with the butter mixture.
Pour the batter into the prepared pan. Smooth the top with a spatula and give the pan a quick spin to even out the batter. Sprinkle with the sliced almonds. Bake in the middle rack of the oven until well risen and golden, 45 to 50 minutes. The center of the cake should spring back when pressed lightly.
Let the cake cool in the pan on a rack until warm to the touch, about 30-minutes. Run a knife around the inside edge of the pan and carefully flip the cake onto the rack to release it from the pan. Peel off the parchment. Gently flip the cake again onto a serving plate. Serve warm or at room temperature, dusted lightly with confectioners’ sugar.
Note: As a couple we do not share a love of caramel. As singles, one of us loves caramel. So in creating this dessert we used the egg yolks from the "nine egg whites" called for in the ingredients, to make a creme anglais, which as it turned out, one of us preferred with the dessert. The other of us ate both portions of the caramel sauce and roasted pear.