This gluten free apple slab pie is packed with apples cooked to tender perfection and surrounded by an extra flaky, lightly sweet pie crust. The perfect way to feed a crowd!
Apple season is the best season of the year
We live in New York, downstate, but we are lucky enough to have lots of apple orchards less than an hour’s drive north. When our kids were little, we took them apple picking every year, sometimes with another family but most of the time it was just us.
I loved those trips, whether we got there early enough in the season that the trees were heavy with ripe apples low enough for our little ones to pick alone or not. And going apple picking is just fun for everyone without being too much time or effort whatever our kids’ ages.
Fall is my favorite season, even more so than spring since in the fall the summer weather is just receding and I take the heat and humidity personally every year. Plus, the clothes are better, and the food just can’t be beat.
You can never have too many apples ?
Unlike some other fruits, like the beloved stone fruits of summer or the ever-pushy zucchini, I believe I never have too many apples. They come in so many different varieties (although I’ll pass on the most recent overly sweet hybrids), and can easily be made into every sort of apple pie and cake.
Even people who insist they don’t care for applesauce will go weak in the knees for homemade applesauce. If your apples seem too numerous or you’re stuck with the bruised ones your little kids picked up off the ground of the orchard, never fear!
Peel, core, and slice them, put them in a heavy-bottom saucepan with a pinch of salt, about a teaspoon of ground cinnamon per every 3 apples, a little sugar or honey, and some water, and sit back and breathe deeply.
How to make an apple slab pie
A slab pie is just a pie baked in a rectangular pan, rather than a pie plate. The proportions are a bit different than a classic pie, and the method differs enough that this slab pie needed its own post here on the blog.
It’s a beautiful thing since it serves so many people at once. There’s no need to blind bake the bottom crust, and both the filling and the crust can be made days ahead of time.
You’ll need a jelly roll pan, which is just like a rimmed baking sheet or quarter sheet pan, but a little larger at about 10- x 15- x 1-inch. I purchased a few heavy-duty nonstick jelly roll pans to find a favorite (my pick is the USA Pans jelly roll pan and that’s an affiliate link but please shop around). It’s nice to have one that’s nonstick, but it’s not essential.
If you don’t have a jelly roll pan, you can use a standard 9-inch x 13-inch baking pan, but that will have higher sides which will make shaping the pie more difficult (but not impossible).
If you’d like to watch the crust being made, it’s a slight variation of our extra flaky gluten free pie crust. Click on over there and watch the video.
Here, I found that with such a large quantity of crust, grating very cold butter rather than chopping it and flattening each piece in the flour created the ease I was hoping for without sacrificing flakiness. The pie crust is divided in two, and the bottom crust pressed into the bottom and up the sides of the pan.
When you bake a slab pie, the filling is as responsible for keeping the shape of the as the pan itself. For that reason, I prefer to chop the peeled and cored apples rather than slice them as you would in a more traditional pie, like our Dutch apple pie.
Cooking the apple filling just until the apples are fork-tender allows the sugar to dissolve and the starch to activate before baking. Plus, larger apple pieces would take too long to bake until tender before the crust burned if you tried to bake them from raw in the oven. Just be sure to cool the filling after cooking it, so it doesn’t melt the bottom crust before the pie is ready for the hot oven.
If your apples are extra sweet, feel free to cut back on the brown sugar in the filling. Try using less sugar, cooking down the filling, and then adding a bit more to taste.
Ingredients and substitutions
Dairy-free: The filling is naturally dairy-free, but the crust calls for plenty of butter—and even some sour cream. My favorite dairy-free substitute for butter in pastry is Melt brand vegan butter. Miyoko’s Kitchen vegan butter is a close second.
I don’t recommend Earth Balance buttery sticks for pie crust. They have a ton of moisture when tends to cause the crust to leak and never become flaky.
If you can’t find Melt, try using Spectrum nonhydrogenated vegetable shortening (butter-flavored is best here). You’ll definitely want to brush the crust with the egg wash, though, as shortening doesn’t brown particularly well.
To replace the sour cream in the pie crust, you can try straining plain nondairy yogurt until it’s the consistency of Greek-style yogurt. Alternatively, try using my classic gluten free pie crust recipe, multiplying the ingredients by 3, and just replacing the butter as described above.
That’s the crust we used in our recipe for classic gluten free apple pie, and it works great. The extra flaky-style crust we use here is just next-level, but not essential.
Egg-free: Luckily, the only egg in this recipe is in the egg wash that is used to brush the bottom crust under the filling, and then the top of the crust. You can replace the egg wash on the top crust with heavy whipping cream or coconut cream for a nondairy alternative.
The egg wash that is brushed underneath the filling, on the bottom crust, is used to help seal the bottom crust so it doesn’t get soggy during baking. There isn’t really a viable alternative, so just leave it out. The crust should be fine without it.
Cornstarch: In place of the cornstarch in the filling, try tapioca starch or arrowroot powder. Either should help thicken the filling just as well.
I do recommend using a higher starch blend for the pie crust, as it makes for a lighter, flakier crust. In place of the cornstarch in my Cup4Cup-style blends, try using arrowroot or potato starch.
The apples: As I mentioned above, I really don’t care for many of the newer-to-me apple hybrids, like Jazz and Rave. They taste too sweet and not tart enough for my taste.
For eating, my favorite apples are Macintosh and Empire (is that just a NY apple ??). For baking, I like a mix since that tends to create complexity (in a good way) and depth of flavor.
I do have to nearly insist that you use at least some Granny Smith apples since they are an apple pie baker’s dream: they hold up really well and provide that classic sweet-and-tart taste. Somewhat surprisingly, yellow/Golden Delicious apples are also a good choice to mix in to your filling.
Oh, and there are typically three medium-sized apples in a pound. That might be a useful fact for reference.
Gluten Free Apple Slab Pie
For the crust
3 3/4 cups (525 g) all purpose gluten free flour (I highly recommend my Better Than Cup4Cup blend), plus more for sprinkling
1 3/4 teaspoons xanthan gum (omit if your blend already contains it)
3/4 teaspoon baking powder
1 teaspoon kosher salt
15 tablespoons (210 g) unsalted butter, chilled and grated
1 1/4 cups (300 g) sour cream, chilled
Ice water by the teaspoonful, as necessary
Egg wash (1 egg + 1 tablespoon water or any kind of milk, beaten), for brushing
For the apple pie filling
12 medium-sized firm apples (about 4 pounds) (a mixture of Granny Smith, yellow, and Macintosh or Empire apples works great), peeled, cored and chopped
1/2 cup (72 g) cornstarch
3/4 cup (164 g) packed light brown sugar
1 teaspoon kosher salt
1 teaspoon ground cinnamon
1 cup (8 fluid ounces) lukewarm water
For the glaze
1/2 cup (58 g) confectioners’ sugar
1 teaspoon lukewarm water, plus more as necessary
First, make the pie crust dough. In a large bowl, place the flour, xanthan gum, baking powder, and salt, and whisk to combine well. Add the grated, chilled butter, and toss to coat it in the dry ingredients. Add the sour cream, and mix to moisten the dry ingredients with the sour cream. The dough should be shaggy and somewhat crumbly. Knead the dough together with clean hands until it begins to come together. Add ice water by the teaspoon only if necessary for the dough to hold together. Divide the dough into two equal portions, turn each piece out onto a separate sheet of plastic wrap, and press into a disk as you close the plastic wrap around the dough. It will still seem rough. Place the two pieces of dough in the refrigerator to chill for 30 minutes.
Once the dough has chilled, turn out one piece of it onto a lightly floured surface. Sprinkle the dough lightly with more flour, and roll it out with a rolling pin into a rectangle that is about 1 inch thick, moving the dough frequently and sprinkling it lightly with flour if it begins to stick. Fold the dough over on itself like you would a business letter. Sprinkle the dough again lightly with flour, and roll out it out once again into a rectangle about 1 inch thick. Once or twice more, sprinkle the dough lightly with flour, roll it out, and fold it over on itself like you would a business letter, then wrap it tightly and place it back in the refrigerator to chill for about 2 hours. Repeat with the other piece of dough. This entire dough preparation can be done up to a week in advance, and stored in the refrigerator provided it is wrapped very tightly.
When the dough is nearly chilled, make the filling. In a medium, heavy-bottom saucepan, place all of the filling ingredients and cook over medium heat, stirring occasionally, until the apples are just fork tender (7 to 10 minutes). Remove from the heat and allow to cool to warm room temperature.
Prepare a 10- x 15- inch jelly roll pan. If your pan is nonstick, don’t oil it. If it isn’t spray it lightly with cooking oil spray and set it aside. As the filling cools, remove one of the pieces of pie crust from the refrigerator. On a very lightly floured surface, roll out the dough into an 18 inch x 12-inch rectangle. It should be about 1/4-inch thick. Trim any especially jagged edges. Fold the crust in half, and lift it carefully onto the prepared jelly roll pan in the proper orientation and into the edges of the pan. Fold any slightly overhung edges under themselves to secure them. Brush the bottom of the crust lightly with the egg wash, and place it in the refrigerator to stay cold. Preheat your oven to 375° F.
Remove the remaining disk of pie crust from the refrigerator, and turn it out onto a lightly floured flat surface. Roll the dough into a 12-inch x 15-inch rectangle. It should be about 1/4-inch thick. Trim any especially jagged edges. Pour the prepared filling on top of the crust, and spread out into an even layer. Lift the top crust onto the top of the pan, fold the top crust over the bottom, and crimp the edges together to seal them, using the knuckle of one hand and the fingertips of the other. Using a sharp knife or pastry wheel, cut small vents all over on the top crust, slicing all the way through to the filling. Brush the top crust liberally with the egg wash.
Place the pan in the center of the preheated oven and bake until the crust is golden brown, about 45 minutes. Transfer to a wire rack to cool completely. When the pie is nearly cool, make the glaze by adding the water slowly to the confectioners’ sugar in a small bowl, stirring constantly until you have a very thick paste. Add more water by the droplet until the glaze is thickly pourable. Drizzle on top of the cooled pie and allow to set briefly before slicing and serving.