How to Follow
For the purpose of laying the groundwork: Gather the flour in a large, roomy basin. Equalize the sugar and salt. After adding the butter pieces, sprinkle the flour over them. Use the index fingers of both hands to crack the butter into pea-sized bits. Alternate methods include using a robust pastry blender or two knives. I like working with my hands.
Once the mixture seems essentially unchanged, somewhat crumbly, and the butter has been chopped into tiny pieces, include half a cup of water with the help of a rubber spatula. After the dough starts to come together, mix in the water until it’s absorbed. When working with dry, crumbly dough, gradually add water until a cohesive mass is formed. The dough should be mixed by hand until it forms a soft, somewhat loose ball. Make two somewhat larger pieces of pie dough by cutting the dough in half. For the base of the crust, you’ll want to use the larger piece. Shape one half into a rectangle that is about 1 inch thick on top of a sheet of plastic wrap. To ensure the dough stays together, you may use plastic wrap if needed. Proceed in a similar manner with the remaining dough. Allow the dough to cool in the refrigerator for a minimum of two hours before to use.
In a large dish, combine the apple chunks with the lemon juice to make the filling. The sugar, cornstarch, cinnamon, nutmeg, allspice, and salt should be mixed together in a medium basin. Before setting the apples aside, coat them well with the sugar and spice mixture.
In order to assemble the slab pie: Preheat the oven to 375 F degrees. A baking sheet with dimensions of 10 by 15 inches and a depth of 1 inch should have parchment paper laid down on its base. Just because your pan isn’t exactly the same size as mine doesn’t mean this recipe won’t work; in fact, it means you’ll have more dough than you need.
Roll out the large ball of dough on a floured board into a rectangle that is 18×13 inches in size. Before placing the dough in the pan, be sure to fold over the edges. Press the dough gently into the pan’s interior and corners. While you shape the second ball of dough into a rectangle measuring 16 by 11 inches, place the pan in the refrigerator or freezer to keep it cool.
Remove the pan from the refrigerator or freezer. Toss the dough in the pan with the apples and their juices. The apples will boil down and become much smaller, so don’t be fooled by their appearance. On top of the apples, place the second piece of dough. Make sure that the dough is cut in a way that the top and bottom edges hang over the pan by about ¾ inch. Use your fingers to firmly close the edges.
To finish the dough, brush it with a thick cream or egg wash. To release steam during baking, score the dough several times with a sharp knife into 1-inch slices. If you want to avoid sticking the bottom of your oven to the pan in the event of a spill, place the whole sheet on a larger baking tray.
To get a beautiful golden brown top with filling that is bubbling through the crust holes, bake for 40 to 45 minutes. Wait at least 45 minutes for the pan to cool on a metal rack before slicing and serving.