- For the Marmalade:
- 2 large tangerines, scrubbed
- 2 cups water
- 1 cup sugar
- 1/8 teaspoon salt
- For the Cake:
- 3/4 cup plus 1 tablespoon extra-virgin olive oil
- 3/4 cup sugar
- 2 large eggs
- 1 tablespoon finely grated tangerine zest
- 1/2 teaspoon salt
- 2/3 cup buttermilk
- 1 1/2 cups all-purpose flour
- 2 teaspoons baking powder
- 1 teaspoon baking soda
- 2 tablespoons confectioners’ sugar
For the marmalade: Place a saucer in the freezer. Cut tangerines in quarters, then remove the peels. Coarsely chop the flesh, removing and discarding any seeds. Using a spoon, scrape off any excess pith from the tangerine peels, then slice them into 1/8-inch strips.
Place orange flesh, peels, and water in medium heavy-bottomed saucepan. Bring mixture to boil over high heat, then reduce heat to medium and simmer, stirring occasionally, until rinds are tender, about 30 minutes.
Stir in sugar and increase heat to medium-high. Stir until mixture thickens and darkens in color, 15 to 20 minutes.
To test the marmalade, spoon 1 teaspoon onto the chilled saucer and allow to rest for 30 seconds. If, when tilted, the mixture moves only slightly, the marmalade is done. If not, continue to cook, repeating the plate test every 2 minutes.
Cool marmalade to room temperature and serve with cake or, spread on cooled cake while marmalade is still warm.
For the cake: Adjust oven rack to middle position and preheat oven to 350°F. Grease 9-inch round baking pan with 1 tablespoon olive oil.
Beat sugar and eggs on medium-high speed until pale yellow and foamy, 2 to 3 minutes. Add tangerine zest, salt, buttermilk, and olive oil and beat until thoroughly combined, about 1 minute.
Whisk together flour, baking powder, and baking soda in small bowl. Decrease mixer speed to lowest setting and add flour mixture. Beat just until combined, scraping the sides and bottom of bowl with rubber spatula as necessary.
Scrape batter into prepared pan and bake until cake tester inserted in center of cake comes out clean, 30 to 35 minutes
Cool cake in pan 10 minutes, then turn over onto plate and invert onto cooling rack. Cool completely, about 1 hour.
Transfer cake to serving platter. Sift confectioners’ sugar over cake.