Serves 8 to 10
- 1/2 cup olive oil, plus more for the cake pan
- 1 1/4 cup all purpose flour, plus more for the cake pan
- 1 teaspoon baking powder
- 1/2 teaspoon baking soda
- Pinch salt
- 2 large eggs, plus 4 large egg whites
- 1 cup sugar, plus more for sprinkling
- Grated zest of 1 lemon
- Grated zest of 1 small orange
- 1 teaspoon pure vanilla extract
Preheat oven to 350 degrees. Brush an 8 or 9 inch round cake pan with olive oil and dust with flour. Place a circle of parchment in the bottom. Sift the flour, baking soda, and salt onto a sheet of parchment.
In the bowl of an electric mixer fitted with the whisk attachment, whisk the 4 egg whites until foamy. Add 1/4 cup of the sugar and beat on high until firm peaks form, about 2 minutes.
In a clean mixer bowl, combine the whole eggs, remaining 3/4 cup sugar, lemon zest, orange zest, and vanilla. Whisk on high until foamy, about 1 minute. On low, add half of the flour mixture, then all of the olive oil, finishing with the remaining flour. Remove the bowl and add about a third of the egg whites. Mix in by hand to lighten the batter. Add the remaining egg whites and gently fold into the batter. Pour into the prepared pan and sprinkle the top with sugar. Bake until puffed and a tester inserted in the center comes out clean, 30 to 40 minutes. Cool on a rack for 10 minutes, then unmold and cool completely.