Instructions

  1. Preheat oven to 350 and grease an 11x7 baking pan.
  2. Combine flours and powdered sugar; cut in butter until mixture resembles coase crumbs (mixture will seem powdery, but will come together while baking).
  3. Press mixture to bottom on baking pan and bake for 12 minutes.
  4. Meanwhile, gently combine sugars, flour, egg whites and vanilla. Stir in rhubarb.
  5. Pour mixture over warm crust and bake for 35-40 minutes until wooden pick comes out clean.
  6. Cool on wire rack, can be served warm.
  7. Store in refrigerator.