Description
A large, crowd-pleasing slab pie featuring a tart raspberry and rhubarb filling with a flaky, buttery lattice crust, perfect for gatherings.
Ingredients
For the crust
48 tbsp (678 g) unsalted butter, cold, divided
5 cups (600 g) all purpose flour, divided
1¼ cups (300 g) whole wheat pastry flour, divided
6 tbsp (76 g) sugar, divided
3 tsp (18 g) fine sea salt, divided
1 cup (236 g) water, cold, divided
For the filling
1½ lb (681 g) rhubarb
1 lb (454 g) raspberries
2 cups (400 g) sugar
zest of 1 orange
2 vanilla beans
¼ cup + 2 tbsp (44 g) arrowroot powder
1 tsp fine sea salt
For baking the pie
1 large egg
pinch of fine sea salt
2 tbsp (26 g) demerara sugar
Instructions
- Step 1: To make the first half of the dough, cut 24 tbsp of butter into ½-inch pieces and freeze for 10 minutes.
- Step 2: In a stand mixer with a paddle attachment, combine half of the all purpose flour (300 g), half of the whole wheat pastry flour (150 g), half of the sugar (38 g), and half of the salt (9 g). Mix on low to combine.
- Step 3: Add the frozen butter to the mixer and mix on low for 1-2 minutes until coarse crumbs form. Add half of the cold water (118 g) and mix until the dough just comes together.
- Step 4: Turn the dough onto a work surface, pat into a rectangular block, and wrap in plastic wrap. Roll it to ½-inch thickness and refrigerate for at least 2 hours or overnight.
- Step 5: Repeat steps 1-4 with the remaining half of the crust ingredients to create a second block of dough. Chill both blocks.
- Step 6: When ready to bake, let both dough blocks rest at room temperature for 10-15 minutes. Grease a jelly roll pan.
- Step 7: On a floured surface, roll one block of dough into a 15×20 inch rectangle. Place it in the prepared pan, guiding it into the corners. Trim the dough to leave a 1-inch overhang. Form the trimmings into a square block. Place the pan and the trimmings block in the fridge.
- Step 8: For the lattice, roll the second block of dough into a 15×20-inch rectangle on parchment paper placed on an upside-down baking sheet. Chill for 30 minutes.
- Step 9: Roll the block of dough trimmings into a 12-inch square on parchment and chill for 30 minutes.
- Step 10: Remove the lattice dough and the rolled trimmings. Cut both lengthwise into 1-inch wide strips. Place all strips back in the refrigerator while you prepare the filling.
- Step 11: For the filling, trim the rhubarb and cut into ½-inch pieces. Place in a large bowl with the raspberries.
- Step 12: In a separate bowl, use your fingers to mix the sugar, orange zest, and seeds from the vanilla beans. Stir in the arrowroot powder and salt. Add this mixture to the fruit and gently combine.
- Step 13: Remove the pie shell from the refrigerator and scoop the filling into it, spreading it in an even layer.
- Step 14: Remove the lattice strips from the refrigerator. Weave the strips over the filling to form a lattice top. Trim the edges of the lattice flush with the inside rim of the pan.
- Step 15: Gently roll the 1-inch overhang of the bottom crust up to the rim of the pan and crimp to seal the edges. Chill the entire pie for 30 minutes.
- Step 16: Preheat the oven to 375F.
- Step 17: In a small bowl, whisk the egg with a pinch of salt to make an egg wash. Remove the pie from the refrigerator, brush the egg wash over the crust, and sprinkle with demerara sugar.
- Step 18: Place the pie on a parchment-lined baking sheet and bake for 50-60 minutes, rotating halfway through, until the filling is bubbly and the crust is golden brown.
- Step 19: Remove the pie to a cooling rack and let it cool for at least 1 hour before slicing and serving.
Notes
Using very cold butter and water is key to a flaky crust.
Plan ahead as the dough requires at least 2 hours of chilling time before rolling.
Allowing the pie to cool sufficiently before cutting helps the filling set properly.
- Prep Time: 1 hour
- Cook Time: 60 minutes
- Category: Dessert
- Method: Baking
- Cuisine: American