In a large bowl, combine flour, salt and baking powder. Cut in the shortening until the mixture starts to come together and there is pea sized crumbs. Mix together egg yolk and water. Slowly add to the flour mixture, carefully mixing until the dough comes together. Using your hand fold the dough over a few times. Let the dough rest in the fridge for 30 minutes. Cut off a 1/4 of the dough and set aside. Lightly sprinkle flour on your counter top. Roll out the remaining dough into a large rectangle. Transfer the rolled dough onto a 11x15 inch cookie sheet.
Filling
Peel the apples and cut them in small pieces. Add the sugars, flour, cinnamon and nutmeg to the apples and mix well. Pour the apple mixture onto the crust and spread out evenly.
Top crust
Lightly sprinkle flour on your counter top. Roll out the remaining dough. Tear of pieces of the rolled dough and place on top of apples. Continue this until all the dough is used.
Baking
Place a piece of tinfoil on the bottom of your oven to help with spills. Bake in a 375 degree oven for 45-50 minutes. Let cool.
Glaze
Dip a fork into the glaze and drizzel over top of the crust. Let cool.