In a mixing bowl, combine flours, baking powder and sugar. Cut in butter until mixture resembles fine crumbs.
Beat half and half with egg yolk. Add to crumb mixture. Stir with fork just till moistened. Gently fold in berries.
Turn out on floured surface and knead gently about 6 times to form a ball. Pat into a circle about 3/4" thick. Carefully place on greased cookie sheet.
Use sharp knife to mark 8 wedges. Don't cut all the way through. Sprinkle with sugar.
Bake at 425 degrees for 20 minutes or till slightly browned. Break into wedges and serve with soft butter.