With the rack in the middle position, preheat the oven to 325°F (165°C). Line two baking sheets with parchment paper.
In a small bowl, combine the egg yolk and water. Set the egg wash aside.
In another bowl, combine the seeds. Set aside.
In a food processor, combine the flours, baking powder, salt and spices. Add the water, oil and molasses. Pulse until the dough begins to form.
On a lightly floured surface, knead the dough for 1 minute or until smooth. Shape into 4 discs. Roll out 1 disc at a time, as thinly as possible, into 12 x 8-inch (30 x 20 cm) irregular rectangles. Place 2 rolled-out dough pieces onto each prepared baking sheet.
Brush the dough with the egg wash. Sprinkle each with 2 tsp of the seeds, pressing lightly.
Bake one sheet at a time for 16 to 18 minutes or until golden brown and crisp. Let the crackers cool completely on the baking sheet.