Pour the boiling water over the prunes and soak for 15 minutes.

Meanwhile, preheat the oven to 350°F. Line a 9" bread pan with parchment then lightly spray with cooking spray and set aside.

After the prunes have soaked, reserve one tablespoon of the soaking liquid and drain the rest. Use a fork to mash the prunes and the 1 tablespoon of soaking liquid into a paste with no big chunks remaining.

In a mixing bowl combine the prune puree, melted butter, dark brown sugar, yolks, orange zest, and vanilla extract. Whisk until combined.

Sprinkle the flour, ginger, allspice, salt, and baking powder over the mixture then stir to combine.

Spread the batter into the prepared loaf pan, sprinkle the walnuts and candied ginger over the top.

Bake for 25 minutes, or until a toothpick inserted into the center comes out clean. Cool in the pan on a wire rack for 10 minutes then remove the cake from the pan. Allow to cool to room temperature then slice into 8 pieces to serve.