Preheat your oven to 350 degrees Fahrenheit, and set rack in middle position
Combine your flour, baking powder, baking soda, cinnamon, ground ginger and salt in a medium sized bowl. Whisk until well combined and then set aside.
In the bowl of your stand mixer (or in another bowl if you will be using a hand held mixer) combine the eggs with the sugar. Beat at medium speed for 3-5 minutes until the mixture is a pale yellow colour. Slowly pour in the oil and then add the vanilla extract. Beat until well combined.
With the mixer set to low, slowly add in half of the flour mixture. Then add in the orange juice. Once everything is incorporated, add the rest of the flour. Mix until just well combined.
Grease a 9 inch spring form pan or round cake pan with some vegetable oil, and pour the batter into the pan. It will be thick.
Arrange the plums on top of your batter with the skin side up in a circular pattern as shown in picture above. Use enough plums so that most of the batter is covered.
Sprinkle one tablespoon of sugar on top of the batter and plums. Don't skip this step, it adds great texture and flavour.
Bake for 50-55 minutes, until the cake is golden and set.
Remove from the oven. If you are using a spring form pan, slowly go around the edge of the cake with a knife to loosen it from the sides. Release the sides of the spring form pan from the pan base slowly and lift off. If using a regular cake pan, let it sit for 10-15 minutes, and then remove from pan by flipping it onto a wire rack. Then flip your cake over again as you want your plums and the sugar coating to be on top.
Let cool on wire rack.
Enjoy!