12 smallish purple Italian purple plums, halved and pitted
1 teaspoon or tablespoon ground cinnamon
Heat oven to 350°F. Sift or whisk together flour, baking powder and salt in a medium bowl. In a larger bowl, cream butter and 1 cup sugar together with an electric mixer until fluffy and light in color. Add the applesauce and eggs, then the dry ingredients, mixing until just combined.
Spoon batter into an ungreased 9-inch springform pan (but if you’re worried, you can always lightly coat it first with butter or a nonstick spray) and smooth the top. Arrange the plums, skin side up, all over the batter, covering it. Sprinkle the top with cinnamon, then remaining sugar.
Bake until cake is golden and a toothpick inserted into a center part of the cake comes out free of batter (but of course not plum juice), about 45 to 50 minutes. Cool on rack.