- ½ cup sifted cake flour
- 1 teaspoon baking powder
- Pinch of salt
- 3 extra-large eggs, separated
- 1/3 cup plus 2 tablespoons sugar (divided)
- 1 teaspoon pure vanilla extract
- 3 drops lemon extract (optional)
- 3 tablespoons unsalted butter, melted
- ¼ teaspoon cream of tartar
- Preheat the oven to 350 degrees.
- Generously butter a 9-inch springform pan.
- Into a medium bowl, sift together the flour, baking powder, and salt. Set aside.
- In a large bowl, beat the egg yolks with an electric mixer on high for 3 minutes. Then, with the mixer still running, gradually add 1/3 cup of the sugar, and continue beating until thick light-yellow ribbons form in the bowl, about 5 minutes more.
- Beat in the vanilla and lemon extracts.
- Sift the flour mixture over the batter, and stir it in by hand until no more white flecks appear. Then blend in the butter.
- In a clean bowl, using clean dry beaters, beat the egg whites and cream of tartar together on high until frothy. Less than a tablespoon at a time, add the remaining 2 tablespoons of sugar and continue beating until stiff peaks form.
- Stir about 1/3 cup of the whites into the batter, then gently fold in the remaining whites (don’t worry if a few white specks remain).
- Gently spoon the batter into the pan.
- Bake the cake just until the center springs back when lightly touched, only about 10 minutes (watch carefully). Let the cake cool in the pan on a wire rack while you continue making the cheesecake filling. Do not remove the cake from the pan.