Place prunes in a heavy pot and cover with water and sugar. Bring to a simmer and cover the pot. Simmer until most of the water has been absorbed. Take from heat, pour off extra liquid and mash. Put aside until time to assemble pie.
Slice apples and put into the heavy pot and cover with water. Add half the cinnamon, ginger, cloves, nutmeg. Simmer for about 15 minutes. Drain in cullender. Pour half the rum extract over apples and sprinkle another teaspoon of cinnamon half the brown sugar and toss.
Make a top crumble for the pie. Take flour and mix with butter, remaining cinnamon, the rest of the oats, and brown sugar. Mix until at a crumb stage.
In empty pie shell, sprinkle half the oatmeal on the bottom. Spoon cooled prunes on top of oatmeal. Add the apple slices. Add on the top crumble to cover the pie. Bake at 375 for 40 minutes.
Mix together powdered sugar and remaining Rum extract... Add water or milk by drops until desired consistency. Pour over finished pie.