This apple custard pie is made in a quarter-sheet pan (9" x 13") and it makes enough to feed a crowd. With a layer of brown sugar custard under a layer of juicy, spiced apples all baked in a nutty cookie crust, this is one excellent pie!
Roll one recipe of nut dough between 2 pieces of 12" x 16" parchment paper until it reaches all the edges and is even in thickness. Be sure to remove parchment periodically and smooth it out so you don't roll wrinkles into your dough.
Freeze the dough, parchment and all, for 5-10 minutes. Carefully peel the parchment from one side of the dough and center the dough, remaining parchment up, over the pan. Peel off the second piece of parchment.
As the dough softens, it will "slump" into the pan. Lift from the edges and gently push inward, guiding the dough into the corners of the pan all the way around. Allow the excess dough to hang over the edges.
To Make the Apples
In a large saucepan, whisk together the water, brown sugar, apple cider vinegar, spices, and salt.
Wash, peel, and cut each apple into 4 pieces around the core. Cut each piece into about 1/8"-1/4" slices. As you finish slicing each apple, drop the slices into the sauce pan and give the apples a quick stir to coat.
When all the apples are in pot, heat over medium heat and bring the mixture to a boil. Reduce the heat and simmer until you like the tenderness of the apples. They won't get much softer in the oven, so make sure you're happy with the texture at this stage. I simmered mine for 30 minutes.
Whisk the cornstarch slurry well, and add it to the apples. Bring to a boil, and allow to boil gently and thicken for about 2 minutes.
Stir in the butter until melted and well combined. Allow the mixture to cool for an hour, stirring occasionally.
To Make the Custard
Whisk all the custard ingredients together in a medium bowl. Allow to sit for five minutes to allow the sugar to dissolve completely, and then whisk again until smooth.
To Assemble and Bake
Place a rack in the center of your oven and put a pizza stone on it. Heat the oven to 375F.
Pour the custard into the prepared pie crust and smooth out with a spatula.
Drop spoonfuls of the cooled apple mixture on top of the custard mixture and spread out as evenly as you can.
Roll the second piece of nut dough out into a 12"x16" rectangle and cut with a straight or fluted dough wheel into 1" strips. Arrange them in a simple lattice over the apples--no need to weave unless you want to--with about 1 1/2" in between.
Trim the strips and overhanging dough from the shell leaving about 1/2" excess all around. Fold the excess in on itself and press down all the way around, either with your fingers or a fork.
Brush the pastry strips and border with eggwash and then sprinkle liberally with coarse sugar or sanding sugar.
Bake for about 45 minutes, until the crust is nicely golden brown and the internal temperature in the center of the pie is about 170F. NOTE: The apple filling will most likely not bubble because of the insulation the custard and dough add. That's why it's important to cook the apples on the stove to your desired degree of tenderness.
Allow the pie to cool for about 30 minutes before slicing and serving.
Notes
Storing
Store leftovers in the pan, covered and refrigerated, for up to 5 days. Rewarm to serve. Freezing is not recommended.
Variations
Make this pie with your favorite fruit. I have made it with peach, and it was excellent. Other stone fruits or berries would work well also. You may need to adjust the amount of thickener you use depending on how juicy your fruit is.Rather than making a lattice crust, just use a full sheet of nut dough for the top crust, cutting vent holes in it with a knife or even a small apple-shaped cutter.Make it a Dutch apple custard pie by swapping the top crust, lattice or not, with a healthy amount of streusel topping.
Tips
Make-Ahead Tips: Make the custard up to 2 days before baking. Make the apples up to 3 days before baking. Make the dough the day before, or make it well ahead and freeze it in sheets. Thaw in the fridge overnight.Rolling each recipe of nut dough between 2 half-sheet-sized pieces of parchment until it reaches the very edges will give you the perfect size to line your 9" x 13" pan.Freezing the rolled dough for 5 or 10 minutes will make it easy to transfer to the pan. As the dough softens, lift from the edges and press the dough into the corners of the pan. Allow excess to hang.