The prune plums are Italian and are smaller than the standard plums you see at the store. They have a very nice dark color and their firmness stands up well in the kuchen. The recipe original recipe was changed slightly by the girl (changes included below) to have cardamom instead of cinnamon. She also added vanilla extract for a bit more depth of flavor.
Adapted from The New Elegant But Easy Cookbook
1/4 pound unsalted butter, softened
3/4 cup plus 1 or 2 tablespoons sugar
1 cup unbleached flour
1 teaspoon baking powder
1/2 teaspoon cardamom or more, to taste
pinch of salt
1 teaspoon vanilla extract
24 halves pitted Italian (prune or purple) plums
cinnamon to taste (can omit this)
1. Arrange a rack in the lower third of the oven. Preheat the oven to 350 degrees.
2. Cream the butter and the 3/4 cup of sugar until pale in color (5 minutes or more is ideal). Sift the flour, baking powder, cardamom, and salt together and add to the butter and sugar mixture. Make a well, add the eggs and vanilla, and beat just to combine. Be careful not to overwork the dough - folding is great for this. Spoon the batter into an ungreased 9- or 10-inch springform pan (or an 8 x 8 square pan). Cover the top with the plums, skin sides down. Mix the cinnamon with the remaining 1 or 2 tablespoons of sugar and sprinkle this over the top.
3. Bake for 40 to 50 minutes, until a cake tester inserted in the center comes out clean. Remove from the oven and let cool; refrigerate or freeze if desired.
4. To serve, let the cake return to room temperature and reheat at 300 degrees until warm, if desired. Serve plain or with vanilla ice cream.