In a large bowl, combine flour, baking powder and baking soda.

In a food processor, combine banana, blueberries, oil, water, egg and vanilla. Puree until smooth. Pour over dry ingredients and mix well. In the bowl and using hands, knead until dough holds together. Transfer to lightly floured surface.

Divide dough into 2 equal pieces. Shape each piece into a log. Flatten the logs to make about 4 inches (10 cm) wide. With a fork, poke holes all over the surface of the logs. Place about 4 inches (10 cm) apart on baking sheet. Bake in preheated oven for 35 to 40 minutes or until firm. Place pan on a rack and let cool for 30 minutes.

Reduce oven temperature to 300 F (150 C). With a sharp knife, cut each log into 1/4-inch/0.5 cm thick slices. Place, cut side down, about 1/2 inch (1 cm) apart on baking sheets. Bake for 30 minutes longer or until hard. Transfer cookies to a rack and let cool completely.

by Bullet