Finely chop the figs (removing the tough stems) and put them into a small saucepan with the orange juice. Bring to a simmer and cook, stirring occasionally, for 20 minutes or until it turns into a soft sort of jam. The texture will depend on the dryness of the figs - add more juice or water if need be. If the mixture seems too chunky, puree it in the food processor once it has softened. (It's tough to chop dried figs in the food processor alone - they tend to be too thick and sticky.)
In a large bowl, beat the butter and sugars until well blended and the mixture has the texture of wet sand. Beat in the egg, molasses, ginger (if using) and vanilla. In a small bowl, stir together the flours, baking powder, baking soda and salt. Add to the wet ingredients and stir with a spatula just until the dough comes together. Wrap in plastic wrap and refrigerate for at least an hour, or overnight.
When you're ready to bake, preheat the oven to 350F. Cut the dough in half and roll one piece out into a rectangle about the size of your cookie sheet - this is easy to do on a piece of parchment or a Silpat baking mat, which can then be slid right onto the baking sheet. Spread the dough with the fig filling. Roll the second piece of dough out to the same size on a piece of waxed paper; lay it over the fig filling, and press it gently to seal the two together a bit. I usually roll the whole thing gently with a rolling pin, being careful that the filling doesn't spill out the sides.
Bake for about 25 minutes, until pale golden and set. Cool for about 10 minutes, then trim the edges and cut the slab into squares or rectangles with a knife, pizza wheel or pastry cutter.