Preheat the oven to 350 degrees.
In a dry skillet over medium-high heat, toast the almonds until light golden brown and fragrant, stirring frequently. Let cool and grind into a fine powder.
Combine the almonds, ginger, cinnamon, nutmeg, and brown sugar in a shallow dish. Brush the apples with the egg white and press into the spice mixture.
Heat the butter in a saucepan over medium heat. Brown the cut side of the apples in the pan for 1 to 2 minutes. Turn the apples over and add 1/2 cup of water and the prune juice. Bring to a boil, then simmer for 1 hour, or until the apples are tender and the sauce is reduced to a thick syrup.
Place an apple half on each of 4 dessert plates and spoon the sauce over each.