Gâteau Pruneau

1           cup whole-wheat flour
1 cup       all-purpose flour
1/2 tsp     salt
2 1/2 tsps  baking powder
1/2 cup     sugar
1 cup       pitted prunes
1           egg
1/3 cup     corn oil
1 cup       milk
1 tsp       vanilla
1/2 cup     chopped walnuts (optional)

Sift first four ingredients into a mixing bowl. Put prunes and sugar in the food processor and chop until raisin-sized. Mix together the egg, oil, milk and vanilla in another container. Make a depression in the dry ingredients and add the prune sugar mixture, walnuts (if using) and the liquid mixture, folding...