Rinse the prunes and cover with 1 cup hot water in a saucepan.
Cover and let prunes soak 1 hour.
Simmer prunes in soaking water 45 to 60 minutes, or until fruit is plump and tender.
Drain and cool slightly; reserve liquid for topping.
Remove pits and cut prunes finely with scissors.
Sift the flour, baking powder, baking soda, salt, cinnamon, and nutmeg together; combine with the prunes and set aside.
Gradually add sugar to shortening, creaming until fluffy.
Add the eggs in thirds, beating well after each addition.
Beating until smooth after each addition, alternately add dry ingredients in fourths and buttermilk in thirds to creamed mixture.
Turn batter into a prepared 9x9x2-inch baking pan.
Bake at 350°F 40 to 45 minutes, or until cake tests done.