Preparation

• Preheat oven at 350 degrees.
  Rinse, and pit plums. Cut in halves and set aside.
  Butter a 10 inch round cake pan, 2 inch deep with a removable bottom.
  In the bowl of an electric mixer, whisk the butter, and sugar until creamy.
  Add egg and egg yolks until creamy and light. Beat in vanilla.
  Stir flour and baking powder into the batter.
  Spread batter in prepared pan.
  Arrange plums on batter, cut side up in concentric rows, overlapping slightly, leaving a margin of about an inch around the edge.
  
  Topping:
  In a mixing bowl, combine flour, sugar and cinnamon.
  Rub mixture to coarse crumbs. Melt butter and stir in.
  Scatter crumbs over plums.
  Bake for 1 hour or until center is firm.
  Cool cake in pan for 15 minutes.