How to Make Blueberry and Rye Slab Pie

Every other Friday, Yossy Arefi from Apt. 2B Baking Co. shares dessert projects that demand a little extra time and effort. Because your weekends should always be sweet.

Today: Feed the masses at your next summer gathering with an ooey, gooey, tasty mess.

Slab pies are pretty easy to love: They require about the same amount of time as a round pie, but they feed a heck of a lot more people; you can fill them with just about any fruit you like; and the crust-to-fruit ratio is spot on. With a lattice top like this one, slab pie looks like the juiciest, most delicious woven blanket you’ve ever seen. I mean, don’t you just want to curl up with this thing?

Slab pies are most often made in a jelly roll pan, but for this version I wanted something that was part slab pie, part giant pop tart, and sturdy enough to hold and eat without a fork, if necessary. I used my favorite rye crust (with a few alterations) for the base, then I filled it with a simple mixture of blueberries, sugar, flour (to thicken all those delicious juices), and some fresh lemon zest and ginger for a little zing. I love the bright flavor of grated fresh ginger in summer pies; it works with just about any fruit. 

I don’t mind pies that are big, juicy messes, so I gave this slab pie a lattice top -- which caused a bit of leakage onto the sheet pan. For a less juicy mess, roll out the second crust and lay it over the berries like you would with a traditional double-crust pie, then fold the bottom edge up over the top and seal it well with a fork. Either way, you’ll have to fight me for a corner piece.

More: Looking for more blueberry messes? Try a schlumpf.

Blueberry Slab Pie

Serves 12 to 16

For the crust:

9 ounces all-purpose flour
9 ounces rye flour
12 ounces unsalted butter, cold and cut into cubes
2 tablespoons sugar
1 teaspoon salt
12 to 16 tablespoons ice water
1 tablespoon apple cider vinegar

To make the crust, combine the flours, sugar, and salt in a bowl. Use your fingers or a pastry cutter to cut in half of the butter until it is the size of peas, then cut in the other half until it is the size lima beans. Some of the butter will be completely worked into the flour, but you should have lots of visible pieces of butter in the dough, too.

Add the apple cider vinegar to the water and make a well in the center of the flour mixture. Use a gentle hand or wooden spoon to mix about 12 tablespoons of water into the flour until just combined. If the dough seems very dry, add more water, a couple of teaspoons at a time. You have added enough water when you can pick up a handful of the dough and squeeze it together without it falling apart. Press the dough together, then split it in half, form it into discs, and wrap each disc in plastic wrap. Chill the dough for at least one hour before using it, or overnight.

More: Learn how to properly roll out pie crust.

For the filling:

5 cups blueberries (about 2 1/2 pints)
1 cup sugar
1/4 cup flour
1 pinch salt
Zest of one lemon
1 teaspoon grated fresh ginger
1 vanilla bean, seeds scraped
1 egg for egg wash
3 tablespoons crunchy sugar to finish

Preheat the oven to 400° F and line a baking sheet with parchment paper.

Gently toss the blueberries, sugar, flour, salt, lemon zest, ginger, and vanilla bean scrapings in a bowl until well combined.

On a lightly floured surface, roll out one piece of dough into a roughly 8- by 12-inch rectangle, 1/4 to 1/8 inch thick; trim the edges so they're straight and even. Gently move the dough to the prepared baking sheet and put the whole thing in the fridge. Use your trimmings to patch any holes in the bottom crust. Roll out the other piece of dough to roughly the same size, erring on the larger side, and set it aside for a moment.

Remove the first rectangle of dough from the fridge and pour the blueberry mixture on top, leaving a generous border of at least 1 1/2 inches around the edges.

To make a lattice top, cut the remaining dough sheet into 1-inch strips. Starting from the top left corner of the pie, lay one strip of dough horizontally and one strip vertically, so that the horizontal strip is on the bottom. Lay a second horizontal strip about 1/2 inch below the top strip so that it overlaps the vertical strip. Fold the top horizontal strip to the left and lay another vertical strip about 1/2 inch to the right of the first one. Next, fold the top horizontal strip back over it. This way, the second vertical strip will go underneath the top horizontal strip and over top of the second horizontal strip. Fold the first vertical strip up and lay down a third horizontal strip. Fold the vertical strip back down. Next, fold the second horizontal strip to the left and place a third vertical strip. Fold the horizontal strip back over the pie. Fold the middle vertical strip up and lay down the fourth horizontal strip. Fold the top and third horizontal strip to the left and place a fourth vertical strip.

More: Don't fear the lattice! Here are some step-by-step photos to walk you through the process.

Continue until all the strips are used up and the top of the pie is covered; you may have to piece some scraps together to make the last few strips of dough. Fold the bottom crust up and over the top of the pie and press firmly with a fork to seal it.

Another option is this: Do not cut the remaining dough into strips, but lay it over the blueberry filling in one piece, and fold the bottom crust up over the top and seal the edges very well by pressing firmly with the tines of a fork. Cut a few vents in the top and proceed with the recipe from there.

Put the baking sheet into the refrigerator or freezer until the crust is very firm. When you are ready to bake, brush the top of the pie with a beaten egg and generously sprinkle it with sugar. Bake the pie until the crust is deep golden brown and the juices are bubbling, 35 to 45 minutes. Cool slightly before cutting into squares and serving with ice cream or whipped cream.

Note: Be prepared! A lattice-topped pie will probably leak, so do not forget to line your pan with parchment paper. And save that corner piece for yourself.

See the full recipe (and save and print it) here.

Photos by Yossy Arefi