In another medium bowl or in a blender, combine the milk, agave nectar or honey, bananas, egg, oil, and vanilla until smooth. Make a well in the center of the dry ingredients and pour in 1/3 of the liquid mixture. Using a spoon, stir until smooth. Add the remaining liquid mixture and stir just until combined. Add the blueberries and prunes, if desired; stir again, but do not over mix. Spoon 1/4 c batter into each prepared muffin cup. Bake for about 14 minutes, or until the tops spring back when pressed gently in the centers. Do not overbake. Cool in the pan on a wire rack for 10 minutes before removing the muffins from the pan. Serve warm, or cool completely on the rack.