Preheat oven to 325 F.
Whisk together the first 6 ingredients in a medium sized bowl.
Whisk 2 eggs and vanilla together in another bowl. Stir into the dry ingredients.
Stir in the walnuts, chocolate chips and cherries.
Turn out on a lightly floured surface, knead gently until dough forms. (This will be sticky.)
Divide dough into 2 portions. Shape each into a rectangle on parchment lined baking sheets.
Beat the remaining egg and water and brush over the top of each portion.
Bake until firm to the touch, about 25 – 35 minutes.
Cool in pans on wire racks until firm, about 10-15 minutes.
Lower oven to 300 F. Using a serrated knife cut the rectangles into ¾ inch slices.
Place slices on baking sheets, cut side down then bake until crisp, about 10-15 min on each side.
Remove from pans to wire racks and cool completely. Store in an airtight container.