Apple and Wild Plum Crumble / Apple and Greengage Crumble / Plum and Apple Crumble

In Mattimeo, this is said to have sweet acorn crumbs in it. I used almonds per my decision against using acorns in general.

Greengage plums can be used to make the apple and greengage crumble mentioned in Outcast of Redwall, which is served with honey thickly spread over it. 

"Plum and apple crumble" is mentioned somewhere. I didn't note the book because there were no specific ingredients or methods mentioned. I figure there's no need to make a different recipe for it.

Filling:
3 cups chopped apples

3 cups chopped plums

1/4 cup brown sugar

1/2 tsp. ground ginger

Topping:
1/2 cup flour (whole wheat, whole wheat pastry, white wheat, or oat flour)

3/4 cup nut flour
1 cup rolled oats
1/4 cup honey

1/4 cup butter, cold, cut into small pieces

Preheat oven to 375 F. 

Stir together the apples, plums, brown sugar, and ginger. Put in a 9" baking dish. Stir the oats, flour, and nut flour together. Cut in the honey and butter until there are no more large chunks. Sprinkle the topping over the fruit. 

Bake for 30 minutes.