Blackberry Slab Pie

4.58 from 7 reviews

When you need to feed a crowd, Blackberry Slab Pie is the way to go. A flakey pastry crust is filled with barely sweetened blackberries and a whisper of lemon. The recipe can be halved for a smaller crowd.

Prep Time: 1

Bake Time: 45

Total Time: 1 45

24 portions

Ingredients
US Customary - Metric

3x recipe Perfect Pie Crust
3 pounds blackberries (fresh or frozen )
10 oz granulated sugar (1 ¼ cups)
1 lemon (zested and juiced)
3 oz corn starch (½ cup)
¼ teaspoons salt
1 egg (for egg wash)
Demerara sugar for topping

Instructions

Make the pie dough according to the recipe and chill at least 2-3 hours or overnight.
Line a 1/2 sheet pan with parchment paper or a silicone baking mat. Divide the pie dough into 2 equal pieces. If the dough is very crumbly, knead a few time to bring it together.
On a lightly floured surface, roll one portion of the dough to a 1/8" thick rectangle at least 20"x16". You can roll a little bigger to get the right thickness. Roll the dough onto the rolling pin to transfer it to the prepared pan. Sprinkle a light layer of flour over the dough in the pan.
Roll the other piece of dough to a 1/8" thick rectangle at least 24" long (about 18" wide). Sprinkle flour over the dough and fold in 1/2, sprinkle with flour and fold again. Place the folded top crust into the pan. Put the pan in the refrigerator to chill while you prepare the filling.
Toss together 3 pounds blackberries, 10 oz granulated sugar, juice and zest from 1 lemon, 3 oz corn starch and ¼ teaspoons salt.
Remove the folded top crust from the pan then pour the berries into the crust. Evenly distribute any clumps of sugar over the berries.
Unfold the top crust. Use a pizza cutter or sharp knife to cut along the long side of the rectangle to even out the edge. Use a ruler to mark 2" increments across the dough. Cut the dough into 2" wide strips. Lay 5 strips, long-ways, evenly spaced over the pie filling. Cut the remaining strips in 1/2 so they are 12" long.
Watch this video to see how to weave a lattice crust. Trim all the top strips so they are just touching the edge of the pan. Trim the bottom crust to about 1/2" over the edge of the pan. Egg wash around the edges. Fold the bottom crust over to enclose the stripes. Use your fingers or a fork to crimp the edges. Egg wash the entire pie and sprinkle with Demerarra or granulated sugar. Chill the assembled pie for 30 minutes.
While the pie chills, preheat the oven to 375 °F. Bake the pie on the bottom rack of the oven until the juices in the middle are bubbling and the crust is golden brown, about 45 minutes.
Serve slightly warm or room temperature.