Pre-heat the oven to 350 degrees. Spray a spring form pan with baking spray. Beat together the butter, sugar and eggs. Add flour, baking powder and salt. Mix well. Transfer to pan and spread batter evenly. Place plums flesh side down into a pattern. Sprinkle with cinnamon sugar and squeeze a bit of lemon juice on the top. Bake for 50 minutes until center is firm to the touch. Cool cake for a few minutes, remove from spring form pan and place on a cake plate. Just before serving, sprinkle with powdered sugar.
Happy new year to those of you who celebrate Roshashana!