In a large mixing bowl, whisk together the flour and sugar. Using your hands, gently toss the butter and lard into the dry mixture. Next, push each large piece of butter in between your thumb and index finger. This will sort of flatten out the butter pieces and break them up.
Working slowly, add the ice water to the dry mixture, one tablespoon at a time, mixing well after each addition. Dough is ready when it holds together in a ball after being pressed, with minimal cracks along the surface. Refer to my entire post all about pie crust for a very in-depth walk-thru.
Divide dough in half, pat into a small square, sprinkle with a few drops of water, and wrap tightly in plastic. Chill in fridge for at least 30 minutes, if not longer, preferably overnight.
When ready to roll out, lightly dust work surface and rolling pin with flour. Roll one batch of dough into a rectangle that is 1 inch larger on all sides than your jellyroll pan. Place the first batch of rolled dough in the pan and prick with a fork. Place in fridge to chill.
Roll out the second crust to another rectangle of the same size and place on cookie sheet or cutting board lined with parchment. Place in fridge to stay cool while you prepare the filling.
For the filling:
Preheat oven to 350 degrees.
In a large bowl pour the lemon juice over the sliced apples and toss to coat. Do the same with the corn starch.
Add the brown sugar, spices, salt, and vanilla extract to the bowl. Tossing to coat.
Pour the filling into the prepared crust in the jellyroll pan and top with the other crust. Fold top crust over the bottom and pinch to seal, crimping with fingertips. Brush crust with egg wash and slice slits in the top to release steam.
Bake in preheated oven 40 - 45 minutes, or until crust is golden brown and apples are tender.
Remove from oven and cool on wire rack for at least one hour.
For the glaze:
When slices are nearly cool, whisk together the 2 cups powdered sugar, 2 tablespoon milk, and 2 tsp. vanilla extract until smooth. Spread glaze over cooled apple slices. Slice into 12 equal squares and serve.
Notes
If preparing the crust a day in advance: remove from refrigerator 15 minutes prior to rolling out. This will help prevent the crust from cracking at the edges when rolling.
If preparing the apples a day in advance: toss with ¼ cup lemon juice and omit the 1 tablespoon lemon juice from the original recipe the following day. Proceed with remaining recipe as written.
I learned my pie crust method from the Pie Whisperer herself, Erin McDowell. I cannot recommend her book, The Fearless Baker, enough!