Step 1

Arrange a rack in the middle of the oven and heat the oven to 350ºF. Generously coat a 9-inch round cake pan at least 2 inches high or preferably springform with cooking spray. Line the bottom of the pan with a parchment paper round.

Step 2

Place 1 1/2 cups granulated sugar in the bowl of a stand mixer (or large bowl if using an electric hand mixer). Finely grate the zest of 1 medium orange into the bowl. Rub the zest and sugar together with your fingers to release as much of the oil in the zest as possible, 1 to 2 minutes. Reserve 1 tablespoon of the orange sugar for sprinkling, preferably in a warm area. Juice the orange (about 1/2 cup).

Step 3

Add 3/4 cup of the extra-virgin olive oil, 2 large eggs, 1 large egg white to the remaining orange sugar. Beat with the whisk attachment on medium-high speed until lightened in color and fluffy, about 5 minutes.

Step 4

Add 2 cups all-purpose flour, 1/2 teaspoon kosher salt, 1/2 teaspoon baking soda, and 1/4 teaspoon baking powder. Beat on low speed until just incorporated, about 1 minute. Add the orange juice, 1 cup sour cream, and 1 teaspoon vanilla extract. Beat on low speed until just incorporated and no streaks remain, about 1 minute.

Step 5

Pour the batter into the baking pan. Place the pan onto a baking sheet.

Step 6

Bake for 30 minutes. Rotate the cake and bake until a tester inserted into the center comes out clean, 20 to 25 minutes more.

Step 7

Place the baking pan on a wire rack and let cool for 10 to 15 minutes. Run a thin knife around the cake to loosen. Remove the sides of the springform pan, or remove the cake from the round cake pan. While still warm, brush the cake all over with the remaining 1 tablespoon extra-virgin olive oil, then sprinkle with the reserved orange sugar. Let cool completely, about 1 1/2 hours.