Yield: 18 to 24
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This berry slab pie is guaranteed to elicit oohs and aahs before the first slice is even cut. And no one will know it’s a cinch to prepare.
Start by tossing no-prep berries—blueberries, raspberries, and blackberries—with sugar, lemon zest, and tapioca for the filling. Instead of applying a top crust, which would hide the beautiful berry hues and trap moisture, sprinkle on a streusel that is flavored liberally with more lemon zest as well as some crystallized ginger; the topping added fresh and zingy pops of flavor to the sweet, bright berries peeking through.
Time: 2 hours, plus 30 minutes chilling and 2 hours cooling
Slab pie dough:
- 24TBS (3 sticks) unsalted butter, divided
- 2¾cups AP flour, divided
- 2TBS sugar
- 1tsp table salt
- ½cup ice water, divided
Streusel:
- 1½cups AP flour
- ½cup packed light brown sugar
- ½cup crystallized ginger, chopped fine
- ¼cup granulated sugar
- 1TBS ground ginger
- 1tsp grated lemon zest
- ¼tsp table salt
- 10TBS unsalted butter, melted and cooled
Filling:
- 1cup granulated sugar
- 6TBS instant tapioca, ground
- 1tsp grated lemon zest
- ¼tsp table salt
- 1¼lb (4 cups) blackberries
- 1¼lb (4 cups) blueberries
- 1¼lb (4 cups) raspberries
You will need an 18 by 13-inch half-sheet pan for this recipe.
You can toss the berry mixture in two bowls if it doesn’t fit in one.
Slab pie dough:
Grate 5 TBS butter on large holes of box grater and place in freezer. Cut remaining 19 TBS butter into ½-inch cubes.
Pulse 1¾ cups flour, sugar, and salt in food processor until combined, 2 pulses. Add cubed butter and process until homogeneous paste forms, 40 to 50 seconds. Using your hands, carefully break paste into 2-inch chunks and redistribute evenly around processor blade. Add the remaining 1 cup flour and pulse until mixture is broken into pieces no larger than 1 inch (most pieces will be much smaller), 4 to 5 pulses. Transfer mixture to bowl. Add grated butter and toss until butter pieces are separated and coated with flour.
Sprinkle ¼ cup ice water over mixture. Toss with rubber spatula until mixture is evenly moistened. Sprinkle remaining ¼ cup ice water over mixture and toss to combine. Press dough with spatula until dough sticks together. Using spatula, divide dough into 2 equal portions. Transfer each portion to a sheet of plastic wrap. Working with 1 portion at a time, draw edges of plastic over dough and press firmly on sides and top to form compact, fissure-free mass. Wrap in plastic and form into a 5 by 6-inch rectangle. Refrigerate dough for at least 2 hours or up to 2 days. Let chilled dough sit on counter to soften slightly, about 10 minutes, before rolling. (Wrapped dough can be frozen for up to 1 month. If frozen, let dough thaw completely on counter before rolling.)
Line the half-sheet pan with parchment paper. Roll each dough square into 16 by 11-inch rectangle on floured counter, stack on prepared sheet, separated by second sheet of parchment. Cover loosely with plastic wrap and refrigerate until dough is firm but still pliable, about 10 minutes.
Using parchment as sling, transfer chilled dough rectangles to counter, discard parchment. Wipe the sheet clean with paper towels and spray with vegetable oil spray. Starting at short side of 1 dough rectangle, loosely roll around rolling pin, then gently unroll over half of long side of prepared sheet, leaving about 2 inches of dough overhanging 3 edges. Repeat with second dough rectangle, unrolling it over empty side of sheet and overlapping first dough piece by ½ inch.
Ease dough into sheet by gently lifting edges of dough with your hand while pressing into sheet bottom with your other hand. Brush overlapping edge of dough rectangles with water and press to seal. Trim overhang to ½ inch beyond edge of sheet. Tuck overhang under itself, folded edge should rest on edge of sheet. Crimp dough evenly around the edge of sheet. Cover loosely with plastic and refrigerate until firm, about 30 minutes.
For the streusel:
Meanwhile, adjust oven racks to lower-middle and lowest positions and heat oven to 375°F. Combine flour, brown sugar, crystallized ginger, granulated sugar, ground ginger, lemon zest, and salt in bowl. Stir in melted butter until mixture is completely moistened, let sit for 10 minutes.
For the filling:
Whisk sugar, tapioca, lemon zest, and salt together in large bowl. Add blackberries, blueberries, and raspberries and gently toss to combine.
Assembly:
Spread berry mixture evenly over chilled dough-lined sheet. Sprinkle streusel evenly over fruit, breaking apart any large chunks. Place a large sheet of aluminum foil directly on the lower rack (to catch any bubbling juices). Place pie on upper rack and bake until crust and streusel are deep golden-brown, and juices are bubbling, 45-60 minutes, rotating sheet halfway through baking.
Let pie cool on wire rack until filling has set, about 2 hours.
Serve.
