Preheat oven to 375° F.Brush bottom and sides of crust,evenly, with egg yolk;bake on baking sheet until light brown,about 5 minutes.
Remove crust from oven. Combine sliced apples,lemon juice,1/2 cup sugar, 1/4 cup brown sugar,3 Tbsp flour,salt,cinnamon and nutmeg. Mix well and spoon into crust.
Mix remaining flour, sugar, brown sugar and butter with fork or pastry blender until crumbly. Sprinkle topping mixture,evenly, over apples.
Bake on baking sheet, about 50 minutes. Cool on wire rack. Serve at room temperature.Servings: 6