• Preheat the oven to 350 degrees F and place a rack in the center of the oven.

Vanilla Cake Batter

• In the bowl of a stand mixer, whisk together the flour, baking soda and baking powder.
• Add in the sugar, eggs, butter, vanilla extract, and sour cream. Using the paddle attachment, on high speed - start slow, beat together all the ingredients for 30 seconds - until light and fluffy.
• Scrape down the sides of the bowl as needed.
• Line a 9" springform pan with parchment paper or grease with a baking spray. If you don't have a springform pan, a standard cake pan will work as well.
• Pour the vanilla batter into the lined pan.

Assemble and Bake the Plum Cake

• Wash and cut the plums in half, then remove the stones. Slice the halves into 1/4" slices (can be thicker if you prefer).
• Arrange the sliced plums, skin side up, onto the top of the vanilla batter. Slightly fan out the slices so that a little of the inside of the plum is showing.
• Continue to add plums until most of the surface is covered, I used 4 small plums here.
• Bake the cake in the preheated oven for 30 minutes. Then, rotate the cake 180 degrees and bake for another 25-30 minutes or until a toothpick inserted in the center of the cake comes out clean.
• Once the cake is finished baking, let it cool for 10 minutes before running a knife along the edge of the cake to loosen it from the pan. Release the spring form and remove the cake from the pan to cool for at least 20 more minutes.
• Optionally dust with powdered sugar before serving.