Preheat oven to 350 degrees F. Set aside a 10x14 inch baking sheet.

In a large bowl, add the sliced apples, granulated and brown sugar, cornstarch, lemon juice, cinnamon, nutmeg, and vanilla. Stir until well incorporated.

On a lightly floured work surface, stack two of the pie crusts on top of eachother, and roll out to about 12x16 inch rectangle.

Fold the pie crust in half or roll it over a rolling pin and place into the 10x14 inch baking sheet. Gently work the crust into the sides and bottom of the pan, allow the excess to drape over the edges.

Pour the apple mixture into the bottom crust. It should be heaping full - the apples will shrink a bit during baking up.

Roll out the second two pie crusts to about 11x15, and lay over the top of the apples. Don’t worry if you get it too large.

Pinch the excess top crust with the bottom crust and tuck it under the button crust.

Cut several slits in the top crust to vent steam while the slab pie bakes.

Place in preheated oven and bake for about 35 minutes or until the crust is lightly browned and the apple pie filling is bubbling.

Remove from the oven and let cool for 15 minutes.

After 15 minutes begin working on the glaze to drizzle on top of the pie while it’s still warm.

In a small bowl, add the melted butter, powdered sugar, and milk. Whisk until thoroughly combined and no lumps remain.

Using a fork or spoon, drizzle over the glaze on top of the warm pie.

Let the pie finish cooling and serve. Add vanilla ice cream or whipped cream on top.