How to Convert Your Favorite Pie into a Slab Pie

Whoever invented slab pies deserves a kiss on the mouth.

Slab pie is an easy, genius pie that serves a crowd with less fuss and less mess. And whether you like the chocolaty creaminess of French Silk, the double-duty flavors of Pumpkin-Pecan or the classic fruity-freshness of our Blueberry Slab Pie, there’s always a good reason to go with a slab over a slice.

Generally speaking, slab pies usually serve 16 people, so no one is going to go hungry with one of these sitting on the dessert table. Most slab pies are delicious beyond measure because they are very crust-forward—and we all know the crust is the best part of a pie.

No pie pan? No problem. Another beautiful thing about a slab pie is that it’s made in a 15x10x1-inch jelly roll pan, which is a little smaller than a typical baking sheet and has a 1-inch lip. They are easy to find and more versatile than a pie pan since they can be used to roast vegetables or bake sheet cakes as well—in fact, you might already have one in your cupboard and not even know it.

But the real question is: “What if I have a beloved standard pie recipe that I want to transform into a slab pie to serve a crowd?” Glad you asked! We consulted our Pillsbury Kitchens experts to weigh in on everything you need to consider before you experiment in your own kitchen.

To dive deeper into the topic of pies (one of our favorite things to talk about), we asked our team in the Pillsbury Kitchens how to easily convert our favorite 9-inch round pies into rectangular, slab-style pies baked in a sheet pan. And while we came out of our discussions with three delicious new classic slab pie recipes—Pumpkin Slab Pie, Apple Slab Pie and Pecan Slab Pie—we also learned that our question could not be answered with a simple formula.

To convert a standard pie to a slab pie, there are several factors to consider, including: the pie crust, the filling and the bake temperatures and times. Let’s cover all three in more detail!

Adjust the Pie Crust

Let’s do some simple math: The general rule is to double the amount of crust you’d need for a 9-inch round standard-size pie to fill a 15x10x1-inch slab pie. For example, if you need one box (14.1 oz) Pillsbury™ refrigerated pie crust for a standard double-crust pie, you’ll need two boxes, or four pie crusts, to make a double-crust slab pie.

For all of our slab pies that use Pillsbury™ refrigerated pie crust, we use two crusts for the base and two crusts for the top crust (for double-crust pies). To prep for a slab pie, remove pie crusts from pouches; on lightly floured surface, unroll and stack crusts on top of the other. Roll to 17x12-inch rectangle (or 18x12-inch, if you have a slightly deeper sheet pan or want a little more wiggle room for fluting the edges). Fit the bottom crust into an ungreased 15x10x1-inch pan, pressing into corners.

For a single-crust slab pie (such as our Sweet Potato Slab Pie with Marshmallow Whipped Topping), fold extra crust even with edges of pan (crust should come to top edge of pan; seal any tears in crust).

For a double-crust slab pie (such as our Strawberry-Rhubarb Slab Pie), unroll and stack remaining two pie crusts on lightly floured surface. Roll to 17x12-inch rectangle, then place pie crust on top of filling. Pinch edges of crusts together to seal, tucking under extra pastry crust, if necessary. Flute or crimp edges. Cut several slits in top crust to allow steam to escape.

If you’re making a lattice-topped pie (like our Blueberry Slab Pie), cut pie crust into 1/2-inch-wide strips with pastry cutter or knife. Place half of the strips across pan diagonally. Weave remaining strips with first strips to form lattice. Trim edges of strips even with edge of bottom crust. Pinch edges of crust together to seal, tucking under pastry crust, if necessary. Flute or crimp edges.

Pre-Bake the Crust on Some (But Not All!) Slab Pies

In testing our slab-style pies, we discovered that in order to make sure the bottom crusts of some of our more liquid-based/custard-based filled pies—such as our Pumpkin Slab Pie and Pecan Slab Pie—the bottom crust must be par-baked, or pre-baked until just browned and set. Pies like pumpkin and pecan have a liquid filling that tends to be higher in fat, which often hinders the full baking of a bottom crust. There are other factors at play when baking a sheet-pan pie, too, that can alter the typical outcome of a pie crust, including the fact that the bake time is often lower to accommodate the shorter height of filling.

In short, when baking a slab pie with a liquid or custard filling, it is best to par-bake the pie crust at a high temperature (usually 425°F for Pillsbury™ refrigerated pie crust) for 6 to 7 minutes (no pricking with a fork needed) before adding the filling. If the crust puffs up during baking, press it down lightly with the back of a flat metal measuring cup.

Expert tip: Don’t forget to adjust the oven temperature for the filling after pre-baking the crust! Many recipes call for two different temperatures for these steps.

However, this is not the case when it comes to fruit-filled pies (such as our Apple Slab Pie) or pies with no-bake fillings (such as our French Silk Slab Pie). For fruit-filled slab pies, we found that the bottom crust bakes through perfectly without a pre-bake because the filling is drier than a custard pie, allowing for better heat conduction throughout. For slab pies with no-bake fillings, just pre-bake the pie crust completely and fill as directed in the recipe.

Consider the Filling

If you’re itching to make your favorite standard pie for a crowd, there are a few tips and tricks to know when it comes to increasing the filling to fit your slab pie.

We found in testing that there is no precise formula for adjusting the amount of filling. While the general rule is to make 1 1/2 times the amount of filling you’d need for a 9-inch round standard-size pie to fill a 15x10x1-inch slab pie, it isn’t always that simple. Here’s what we learned from our Kitchens experts:

• Some ingredients will need to be rounded up or down depending on the original standard pie recipe amounts. Use your judgement on what to round up on and what to round down on, keeping in mind the purpose of that ingredient. For example, if your standard pie recipe calls for 3/4 cup sugar, increasing that amount by 1 1/2 times equates to 1.125—so our recipe developers rounded up to 1 1/4 cups sugar for the slab pie recipe. When it comes to eggs, if a standard pie recipe calls for 3 eggs, you can increase the number to 4 or 5 eggs, depending on your preference (keep in mind that eggs help bind the filling and give it a custard-like texture, but they will also increase the amount of overall filling).
• Take care not to overfill your pie crusts. In the case of our Pumpkin Slab Pie, our recipe developers reduced the proportions of pumpkin and milk called for in our standard Perfect Pumpkin Pie in order to account for spill-over during transfer to the oven and while baking, but increased the remaining ingredients by 1 1/2 times. If you’re converting your own recipe, you could use your judgement on adjusting proportions. Or, you can make 1 1/2 times the amount of filling and just not use all of it for the slab pie (Bonus: Pour any extra filling into an oven-safe custard cup or ramekin and bake a personal-sized crustless pie!).
• Think about flavor, texture and presentation. For our Pecan Slab Pie, we increased the amount of salt in our recipe for Easy Pecan Pie by 1 1/2 times, but we doubled the amount of pecans in order to fully cover the surface of the slab pie. Again, use your judgement on what makes sense when adjusting ingredient amounts.

Expert tip: Don’t forget to increase the amount of topping or garnish, too (because a pie without enough whipped cream is a sad pie)!

Bake Your Pie (and Watch for Doneness)

Though the oven temperature shouldn’t change from the original recipe, bake times could vary greatly. Generally speaking, take the minimum original bake time from your standard pie recipe and reduce it by 10 minutes—that’s when you should first start to check your slab pie for doneness. For example, our Perfect Apple Pie recipe bakes at 425°F for 40 to 45 minutes; our Apple Slab Pie bakes at 425°F for 30 to 35 minutes. Continue to check your pie every 5 minutes until it appears to be fully baked.

For best results, rely heavily on visual cues. For a fully-baked custard pie, the filling should be fully set; for a fully-baked fruit pie, the fruit should be tender and the crust deep golden brown.

Cool Completely

As you would with standard-size pies, it’s best to let your slab pie cool completely on a cooling rack (or refrigerate, depending on the recipe directions) before serving. Once it’s fully cooled or chilled, cut into squares and serve!

Before you get to baking your crowd-sized pies, we have a few more tips for you to ensure ultimate slab pie-baking success:

• If you’re worried about drips, place a layer of foil on the bottom rack of the oven to catch any spills during baking.
• If the crust edges are getting too brown in the oven, loosely cover the entire pie with foil.
• For easier cleanup, roll out the pie crust dough between layers of cooking parchment paper or waxed paper.
• Try to keep the oven door closed during baking as long as possible to maintain even oven temperature. Peek through the oven door to check on the doneness of your slab pie, if possible (otherwise, open and close the oven door quickly).

We encourage you to experiment in the kitchen with converting your favorite pie to a slab pie. However, if you want to give one of our already tried-and-true, Kitchen-tested slab pies a try this season, we fully support you. Above all, have fun: The end result is delicious pie, after all.