Plum Torte

Preheat the oven to 350 degrees F (175 degrees C). Arrange a rack in the lower third of the oven.

Cream butter and 1/2 cup sugar together using an electric mixer in a mixing bowl. Add eggs and mix well. Sift flour, baking powder, and salt into the batter; beat to mix well. Pour into an ungreased 9-inch springform pan.

Cover the batter with plums, skin-side down. Mix 1 tablespoon sugar and cinnamon together in a small bowl and sprinkle over the top.

Bake in the preheated oven until a toothpick inserted into the center comes out clean, 40 to 50 minutes. Remove from the oven and let cool to room temperature, or serve warm.