Step 1: Preheat your oven to 350°F (175°C) and grease a 9-inch springform pan or round cake pan with butter or parchment paper.
Step 2: In a medium bowl, whisk together the flour, baking powder, salt, cinnamon, ginger, and cardamom until well combined.
Step 3: In a large mixing bowl, cream the softened butter and sugar together until light and fluffy, about 3 minutes.
Step 4: Add the eggs one at a time, beating well after each addition, then stir in the vanilla extract.
Step 5: Gradually add the dry ingredients to the wet ingredients, alternating with the milk, starting and ending with the flour mixture.
Step 6: Pour the batter into the prepared pan and smooth the top with a spatula. Arrange the plum wedges on top in a decorative circular pattern.
Step 7: Bake for 45-50 minutes, or until the top is golden and a toothpick inserted into the cake portion comes out clean.
Step 8: Allow the cake to cool in the pan for 20 minutes before releasing the sides of the springform pan. Dust with powdered sugar before serving.