Apple Slab Pie

Preheat oven to 350 degrees F (175 degrees C.) In a large bowl, combine flour sugar, salt and baking powder. Cut in shortening until mixture resembles coarse crumbs. Mix egg yolk and water together and mix into flour until it forms a ball. Roll out to fit the bottom of a 10x15 inch pan. In a large bowl, combine apples, lemon juice, 2 tablespoons flour, sugar and cinnamon. Pour filling into pie crust and dot with 2 tablespoons butter. In a medium bowl, combine 1 cup flour, 1 teaspoon cinnamon, 2/3 cup brown sugar and 2/3 cup butter. Cut in the butter until crumbly, then sprinkle over apples. Bake in the preheated oven for 60 minutes, or until topping is golden brown.