Blueberry Crumb Slab Pie

Why I Like This Recipe

• Serves a crowd. One slab pie will serve 18-24 people. I make my slab pies in a 10×15″ jelly roll pan. This is a great all-around size. It's smaller than the half-sheet baking pans that I typically use, but easier to work with when rolling out the dough.  You can turn any pie recipe into a slab pie by doubling your favorite two-crust pie crust recipe and making about 1 ½ batches of pie filling. Make sure to follow my tips and tricks for achieving a perfectly baked crust (top and bottom)---very important!
• Basic ingredients: My pie crust recipe is a keeper, a variation of my favorite pie crust recipe from Betty Crocker. It uses shortening, butter, and oil for the best texture and flavor. You can use canned pie filling if you'd like (you'll need 3 cans), but I like making blueberry pie filling from scratch. It's super simple and gives you the best flavor.
• The crust is forgiving: Not great at making pie crust? That's ok. Blueberry crumb slab pie tastes delicious regardless, and because it's made with a combination of shortening, oil, and butter, it's a little easier to roll out than an all-butter pie crust. Do your best to roll it into a rectangular shape, but just know that once it's baked up, the golden top and bubbly filling will hide imperfections.
• Stays fresh for several days: Mine have been kept for at least 3 days, making this a great dessert to make the night before you need it.

🥧 5 TIPS FOR BAKING SLAB PIES

Fruit pies, if not properly baked, can end up with an underbaked bottom crust or one that goes soggy after a few hours. This is because fruit fillings break down during baking and leak juice. Having a properly thickened filling (using flour) and making sure your crust is baked properly is key. This is especially important with slab pie because it has a large surface area.

1. Use Crust Dust: I first learned about the miracle of CRUST DUST (see image above) from King Arthur Flour. It's super easy to make, too! Crust dust is a 1:1 ratio of all-purpose flour and sugar. You simply mix the two ingredients together, then sprinkle it over the bottom crust in a THIN layer before adding the pie filling. As the pie bakes, the flour and sugar create a barrier, preventing the juices from soaking into the crust. It really works, too, and once baked, you won't even know it's there.
2. Bake In Bottom ⅓ of Oven: Baking the pie lower in the oven (I bake on the second to bottom rack position) helps the bottom crust to bake evenly.
3. Use a Baking Stone: I swear by baking my pies on top of a preheated baking stone (pizza stone). If you don't have one that's ok! The first two tips will still yield a delicious crust. The baking stone just helps center the heat evenly for the bottom crust.
4. Use a Metal Pan: metal pie pans work better than glass for a golden bottom crust.
5. Don't Worry About Overbaking Your Pie: yep, that's what I said. It's better to slightly overbake the crust vs. underbake. I bake my slab pies for 30 minutes, then loosely cover with foil for another 20-25 minutes. Covering the pie for the last half of the baking process will help the top not get too brown. 

Remember: if the filling isn't bubbling up and almost coming out of the pie, it's not done!

Recipe Ingredients

• Blueberries: You'll need around 36 ounces of fresh or frozen blueberries for this recipe.
• Flour and cornstarch: Fruit pies need a thickener to bind with the sugar and juices for the filling. My preferred thickener is all-purpose flour and a small amount of cornstarch. Flour is also used in the crust.
• Sugar: Blueberries are sweet, but sugar is still needed to create a delicious filling and add even more sweetness.
• Butter, Shortening, and Oil: You'll notice that the pie crust calls for all 3 of these fats. Each one has its purpose and helps create a delicious and flaky pie crust that rolls out easily and does not need to chill. I highly recommend NOT substituting any of these ingredients.
• Milk or buttermilk: You can use buttermilk or a combination of milk and lemon juice. I don't always have buttermilk on hand, so I use the milk and lemon juice hack.
• Brown sugar: adds a caramel flavor to the crumb topping.
• Melted butter: along with butter for the crust you'll also need melted butter for the crumb topping.

See the recipe card for full information on ingredients and quantities.

How To Make Blueberry Slab Pie

Step 1: Mix flour and salt in a large bowl. Cut in shortening using a pastry cutter. Cut in butter until the particles are the size of small peas. Combine the milk and lemon juice in a small bowl. Add oil and milk/lemon mixture to the flour mixture and stir until a soft dough forms. Divide dough into 2 pieces, wrap in plastic and chill for 30 minutes.

Step 2: While the dough chills, make the crumb topping by combining melted butter, brown sugar, sugar, and flour. Refrigerate the topping while you prepare the blueberry pie filling.

Step 3: Roll the chilled pie crust on a lightly floured surface. Keep rolling until it is a 13x18" rustic-looking rectangle. It won't be exact, and that's ok. Place the rectangle into a 10x15" jelly roll pan, allowing the excess to hang over the edge of the pan. Sprinkle crust dust over the pie crust bottom.

Step 4: Pour the blueberry pie filling over the bottom crust. Tuck the excess pie crust into the pan (rolling it forward or behind to tuck into place).

Step 5: Remove crumble topping from the refrigerator. It will be solid, which is exactly what you want. Break it up with a fork into small crumbs (pea-sized). Sprinkle the crumble over the pie filling.

Step 6: Bake the slab pie for 30 minutes. Cover/tent loosely with foil and bake for an additional 20-25 minutes. The top should be GOLDEN and the filling should be bubbling. Allow the pie to cool for at least 2 hours before slicing.

Blueberry Pie FAQs

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