For crust place flour and cold butter cut into small pcs. in food processor. Pulse till butter and flour are combined. Slowly add water, 1 tbsp at a time, will probably need 2-6 tbsp. Pulse as you add water just until dough starts to come together. Remove and form into a ball, wrap with saran wrap and refrigerate for 30 min or while you prepare filling.
FOR CRUMB filling: Place 2/3 c of flour in food processor with 1 cup of brown sugar and 1/4 cup of granulated sugar. Pulse to combine. Add 1/2 c of cold butter cut into small squares, 2/3 c of chopped walnuts, cinnamon and nutmeg, and pulse till crumbly.
Peel and core apples and slice. I used 5 med apples to make about 6 cups of sliced apples. Place in large bowl and pour crumb mixture over top. Mix apples and crumb mixture together well.
Roll dough out as you would when making a pie, this will roll out much larger than a pie crust though. Transfer to a baking sheet sprayed with non stick spray oil.
Place apple crumb mixture in center and fold edges up around the sides. Spray the edges of the crust with spray oil or brush with egg wash or butter and sprinkle raw sugar around edges.
Bake 400° for about 1 hr or till apples are tender.