Apple Slab Pie with Maple Icing

 cups (500g) all-purpose flour

and 1/2 teaspoons salt

granulated sugar

and 3/4 cup (3.5 sticks; 400g) unsalted butter, very cold and cubed

very cold ice water

egg wash: 1 large egg, lightly beaten with 1 Tablespoon (15ml) milk

optional: coarse sugar for sprinkling on top

peeled and chopped apples (about 4 - 5 lbs)1

granulated sugar

all-purpose flour

fresh lemon juice

pure vanilla extract

and 1/2 teaspoons ground cinnamon

ground cloves

ground nutmeg

confectioners' sugar, sifted

 Tablespoons (30ml) pure maple syrup

enough milk or heavy cream to thin (a couple teaspoons)

x15 inch jelly roll baking pan/sheet pan (I like this one and this one)

rolling pin

pastry cutter

pastry brush (I have the 1.5 inch size)