This Peach & Vanilla Slab Pie is the perfect dessert to offer that large crowd gathered at your next backyard barbecue.

What is a slab pie?

A slab pie is a classic pie baked on a rectangular rimmed baking sheet (such as a jelly roll or quarter-sheet pan) rather than in a round pie plate. Depending on the recipe and pan size, it can yield up to 24 servings. Best of all, it features a higher crust-to-filling ratio and is cut into neat squares or bars for easy serving

This one is the perfect crowd-pleaser. The dough is light & flaky with a touch of fresh lemon. The peaches are lightly sweetened with brown sugar & flavored with a generous amount of vanilla.

Before we focus on the peaches, let’s gather what you’ll need for the dough.

Keep in mind that the dought needs to chill for at least two hours. Or, better yet, overnight.

Whole wheat pastry flour – Whole wheat pastry flour is a finely milled, 100% whole grain flour made from soft white wheat. Its low protein (gluten-forming) content combined with whole kernel nutrients makes it the ideal choice for light, tender, and flaky baked goods that do not require yeast. I purchase my whole wheat pastry flour online from Amazon or directly from Sunrise Flour Mill.
Unbleached all-purpose flour – I always use flour that is organic, non-GMO and free of glyphosate. My personal favorite is from a domestic company, Sunrise Flour Mill, located in Minnesota.
Kosher salt – If need be, table salt can be used with caution. Table salt is finer and more dense than kosher salt, so a teaspoon of table salt will contain more actual salt than a teaspoon of kosher salt. When substituting, use about two-thirds the amount of table salt specified in a recipe using kosher salt.
Cold unsalted butter – Cut into small pieces. It is important to use unsalted butter so that the natural butter flavor shines through without the influence of added salt.
Olive oil – I typically use extra-virgin olive oil. It’s a healthy choice and adds a pronounced peppery fruity flavor. Of course, you could use regular olive oil or any neutral oil such as avocado oil or refined coconut oil. It’s advisable to avoid seed oils since they can be toxic when heated.
Lemon juice – Freshly squeezed is best.
Cold water – Room temperature filtered or bottled water is recommended.

Don’t have whole wheat pastry flour in your pantry?

Make your own whole wheat pastry flour at home by combining 1 cup of whole wheat flour (minus 2 tablespoons) with 2 tablespoons of cornstarch or arrowroot starch. Sift the mixture together 3 to 4 times to ensure it is light, aerated, and evenly mixed for tender, flaky baked goods

Add both flours along with one teaspoon salt to the bowl of a food processor.
Quickly pulse two times or until well blended.
Add the cold cubed butter and pulse about 4 to 5 times, until the mixture resembles coarse meal.

Combine the oil, lemon juice & 2/3 cup cold water in a small bowl.
While pulsing, pour oil mixture through food chute.
Process just until the dough comes together and starts to form a shaggy ball.
If necessary, add an additional two tablespoons of cold water, one tablespoon at a time, to bring the dough together.
Be careful not to overprocess.

As shown here, this process is quick and easy when using a food processor.

If you don’t have one, it’s okay. You can do this by hand.

Place the dry ingredients in a large bowl and whisk to blend well.
Then, cut in the cubes of butter with a pastry cutter or two knives.
The wet ingredients can then be added.
Vigorously stir with a wooden spoon until it all comes together to resemble a shaggy ball.

Turn the dough out onto a work surface.
Gently knead until dough just comes together.
Once again, do not overwork the dough.
Divide the dough into two pieces, one roughly 60% of the dough and the other 40%.
Flatten each into a 1-inch-thick disk; wrap each in plastic wrap.
Chill for at least two hours or up to overnight.

When dividing the dough into two pieces, a food scale can be super handy.

Weigh the ball of dough, then do the math so that you have the correct ratio of 60% to 40%.

When the dough has been sufficiently chilled, it’s time to gather what you need for the peach filling.

Ripe peaches – Peeled & sliced. For a more rustic version of this pie, leave the skin on the peaches.
Dark brown sugar – In contrast to its white counterpart, brown sugar boasts a richer, caramel-like, slightly nutty flavor due to its molasses content.
Cornstarch – Or arrowroot starch. Cornstarch, also known as maize starch or cornflour, is a fine, white, powdery substance made from the endosperm of corn kernels. It’s important to note that a significant portion of the corn grown in the US is genetically engineered. I always use arrowroot starch when recipes call for cornstarch. It’s a healthier choice and the outcome is the same.
Vanilla bean paste – Or pure vanilla extract. Vanilla bean paste is a concentrated ingredient made from a blend of pure vanilla extract and vanilla bean seeds, offering a more intense vanilla flavor and visual appeal with its speckled appearance compared to traditional vanilla extract. If you have only vanilla extract, that will be fine as long as it is pure vanilla extract.
Ground cinnamon – Adds a warm spicy-sweet flavor.
Egg yolk – Beaten with water for the final egg wash.

Preheat the oven to 375°F.
Combine the peaches, brown sugar, cornstarch, vanilla bean paste, cinnamon & remaining 1/4 teaspoon salt in a large bowl.
Toss well to combine.
Set aside.

I piled the sliced peaches into what I thought was a large enough bowl. Well, as you can see it just about held it all without spilling over.

Be sure to use a very large bowl to hold at least 12 cups of peaches as well as the added ingredients. It all needs to be mixed really well so that each and every piece of fruit is thoroughly coated with the vanilla-infused sweetness.

I ended up transferring it all into my 8-quart stockpot. That worked.

Set the peaches aside and get to work on the dough.

I’m going to be brutally honest here. The dough is delicious, light and flaky. But it’s a bear to work with. I am so glad I stuck with it and was more than happy with the end result.

I’ve always been intimidated by making my own pie dough. I now realize that making the dough is the easy part. Rolling it out and forming it (on a large scale here) is the real test. I do like a challenge though.

If you’re intimidated by the homemade dough like I was, there’s no reason why you couldn’t try making this (especially the first time) with pre-made pie dough. Pillsbury refrigerated pie crusts would work. You would need two packages, though. This is a really large pie.

Remove the dough disks from the refrigerator and unwrap.
Place the larger dough disk between two lightly floured sheets of parchment paper or plastic wrap.
Roll into a very thin 19- x 13-inch rectangle.
Using a thin pan or cutting board for support, carefully slide dough from the plastic wrap onto a 17- x 11-inch rimmed baking sheet.
Remove the top layer of plastic wrap and press the dough into all corners of the baking sheet.

Transferring the rolled out dough onto the baking sheet is probably the hardest part. You can follow the standard method or give my method a try:

The dough will have been rolled out between two sheets of plastic wrap.
When you achieve the desired shape, slide a large flat-edged baking sheet underneath.
Remove the top layer of wrap.
Place the 17″ by 11″ rimmed baking sheet upside down over the dough.
Using the flat-edged cookie sheet as a support, flip the entire stack over.
The dough should now be resting in its intended baking vessel.
If some of the dough breaks off during the transfer, just place the broken piece where needed.
Cover that area with plastic wrap and roll over it again to mend it.

Spoon the peach mixture evenly over dough.
Place the second (smaller) dough disk between two lightly floured sheets of parchment or plastic wrap.
Roll into a very thin 11- x 17-inch rectangle.
Cut the dough lengthwise into 3/4-inch-thick strips.
Arrange the strips in a lattice pattern over the peach mixture.
Crimp the edges to seal, using excess dough if necessary.

If you haven’t formed a lattice patterned pie crust before, it’s way easier than it seems.

If the dough strips break off as you are working with them, just piece them back together and smooth it out with your fingertip.
It doesn’t have to be absolutely perfect.
Use any excess dough to seal and crimp the edges.
Just keep in mind …rustic is good.

If you’re new at this, take a look at this video and tutorial.

Whisk together one egg yolk and one teaspoon room-temperature water in a small bowl.
Brush dough lattice evenly with the egg yolk mixture.

Bake at 375°F until filling is thick and bubbly and crust is browned, about 50 to 55 minutes.
Cool at least 20 minutes before serving.

Get ready to wow the crowd with your homemade Peach & Vanilla Slab Pie.

When you’re ready to serve this goodness, be sure to offer a scoop of vanilla ice cream along with the pie.

It’s likely that not too many folks will turn that down.