Preheat oven to 350°F. Lightly oil an 8x4 inch loaf pan. In food processor, process prunes and water until puréed. In a bowl, whisk together the prune purée and bananas. Whisk in the sugar, eggs and oil until incorporated. In a separate bowl, whisk together the flour, millet, flaxseed meal, baking soda, salt and spices. Add the prune blend and stir to combine. Pour the batter into the prepared pan and sprinkle the remaining walnuts on top. Bake until a cake tester inserted into the center of the loaf comes out clean, about 55 minutes. Cool in the pan for 10 minutes. Turn the loaf out onto a wire rack and cool completely.