1

Preheat oven to 350°F. Coat a 9-inch round cake pan with cooking spray.

2

Prep oranges: Finely zest 1 orange (you'll have about 1 Tbsp zest); set zest aside. Juice that orange, plus 1 more (you'll have about 1/2 cup juice); set juice aside. Thinly slice remaining oranges; set aside (leaving peels on or off - the choice is yours).

3

In a small bowl, mix brown sugar, cornstarch, and ¼ tsp cinnamon; sprinkle 3 Tbsp mixture in bottom of prepared pan. Arrange orange slices in pan in an even layer, with some curving up the sides of pan. Sprinkle on remaining brown sugar mixture; set aside.

4

In a large bowl, combine flour, granulated sugar, baking powder, baking soda, salt, and remaining ¼ tsp cinnamon.

5

In another bowl, whisk together oil, reserved orange zest and juice, eggs, egg white, yogurt, and vanilla. Continue to beat ingredients until smooth and yogurt is fully incorporated.

6

Fold half of wet ingredients into dry ingredients and whisk until combined. Add remaining wet ingredients; whisk 1 minute.

7

Pour batter into pan over oranges; let rest for 3 minutes. Bake cake until a toothpick inserted in center comes out clean, 35-40 minutes. Remove from oven; let cool on a wire rack.

8

With a knife or spatula, loosen cake edges from pan. Place a plate or platter on top of pan, turn pan over, and carefully lift pan off cake. Dust with powdered sugar; slice into 16 pieces and serve.