Preheat oven to 375 degrees F. Lightly grease a large baking sheet.

In a large bowl, mix together flours, sugar, baking soda, baking powder, salt and butter. Stir in 1 cup buttermilk and egg. Turn dough out onto a lightly floured surface and knead slightly. Mix in the prunes.

Form dough into a round and place on prepared baking sheet. In a small bowl, combine melted butter with 2 tablespoons buttermilk; brush loaf with this mixture. Use a sharp knife to cut an 'X' into the top of the loaf.

Bake in preheated oven for 50 to 60 minutes, or until a toothpick inserted into the center of the loaf comes out clean. For an extra glossy look, continue to brush the loaf with the butter mixture while it bakes.