Set oven to 350 degrees.
Cream butter and sugar with mixer for a couple of minutes, until soft and fluffy. Stir in vanilla and eggs. Set aside.
Whisk together flour, baking powder, salt, cinnamon, nutmeg and cardamom.
Alternate mixing flour mixture and milk into creamed butter until thoroughly combined.
Pour thick batter into a greased cake pan. I like to use a springform pan so everyone can see the prettiness of the cake.
Place plum slices in a circular pattern on the cake until most of the batter is covered.
Bake in oven for 1 hour to 1 hour 10 min until done.
After cooled sprinkle powder sugar on top. (Optional)