Instructions
Preheat the oven to 350°F (175°C). Line the bottom of a 10-inch (26 cm) round cake pan with parchment paper and lightly grease the sides.
In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.
Wash the plums, remove the pits, and cut each plum into four pieces. Place them in a bowl, sprinkle with 1 tablespoon of granulated sugar, and gently toss to coat.
In a large mixing bowl, whisk together the eggs, ⅔ cup granulated sugar, oil, yogurt, and vanilla extract until smooth and evenly combined.Add the dry ingredients to the wet ingredients. Mix gently just until the batter is smooth and no dry streaks or large lumps of flour remain. Do not overmix.
In a large mixing bowl, whisk together the eggs, ⅔ cup granulated sugar, oil, yogurt, and vanilla extract until smooth and evenly combined.Add the dry ingredients to the wet ingredients. Mix gently just until the batter is smooth and no dry streaks or large lumps of flour remain. Do not overmix.
Pour half of the batter into the prepared cake pan and spread it into an even layer. Arrange half of the plums over the batter with the skin side facing up.
Pour the remaining batter over the plums and gently spread it evenly. Arrange the remaining plum pieces over the top, again with the skin side facing up.
Bake for 40-50 minutes, or until the top is golden and a toothpick inserted into the center of the cake, away from the fruit, comes out clean or with a few moist crumbs.
Remove the cake from the oven and allow it to cool in the pan for approximately 1 hour.
Carefully loosen the edges, remove the cake from the pan, and transfer it to a large serving plate.
Dust with powdered sugar before slicing and serving.