This Raspberry-Rhubarb Slab Pie is a celebration of vibrant seasonal fruit, wrapped in a buttery, flaky crust and finished with a delicate vanilla glaze. Unlike traditional round pies, slab pies are baked in a rectangular sheet pan, making them ideal for serving a crowd. The combination of tart rhubarb and juicy raspberries creates a jammy, ruby-red filling that’s both nostalgic and refreshing. With every bite, you get a perfect balance of sweet and tangy, soft and crisp—a rustic dessert that’s as beautiful as it is delicious.
Ingredients
For the Crust:
- 3¼ cups all-purpose flour
- 1 teaspoon salt
- 1 cup cold butter, cubed
- ¾ cup 2% milk
- 1 large egg yolk
For the Filling:
- 2 cups granulated sugar
- ⅓ cup cornstarch
- 5 cups fresh or frozen raspberries (thawed and drained if frozen)
- 3 cups chopped rhubarb
For the Vanilla Icing:
- 1¼ cups confectioners’ sugar
- ½ teaspoon vanilla extract
- 6 teaspoons milk (adjust for consistency)
Instructions
1. Make the Pie Dough
- In a large bowl, whisk together flour and salt.
- Cut in the cold butter using a pastry cutter or your fingers until the mixture resembles coarse crumbs.
- In a small bowl, whisk the egg yolk into the milk. Gradually add this to the flour mixture, stirring with a fork until the dough just comes together.
- Divide the dough into two portions, one slightly larger than the other. Wrap each in plastic wrap and refrigerate for at least 1 hour.
2. Prepare the Filling
- In a large bowl, mix sugar and cornstarch.
- Add raspberries and rhubarb, tossing gently to coat. Set aside.
3. Assemble the Pie
- Preheat oven to 375°F (190°C).
- Roll out the larger dough portion between two sheets of floured wax paper into an 18×13-inch rectangle.
- Transfer to an ungreased 15x10x1-inch baking pan, pressing into the corners and trimming the edges.
- Spread the fruit filling evenly over the crust.
- Roll out the second dough portion and place it over the filling.
- Fold the bottom crust over the top edges and crimp to seal. Prick the top crust with a fork to allow steam to escape.
4. Bake
- Bake for 45–55 minutes, or until the crust is golden brown and the filling is bubbling.
- Let the pie cool completely on a wire rack before icing.
5. Make the Icing
- In a small bowl, whisk together confectioners’ sugar, vanilla, and milk until smooth.
- Drizzle over the cooled pie using a spoon or piping bag.
6. Serve
- Cut into squares and serve as-is or with a scoop of vanilla ice cream or whipped cream.
Tips & Variations
- Fruit Swaps: No raspberries? Try strawberries, blackberries, or cherries.
- Frozen Fruit: Works well—just thaw and drain excess liquid.
- Add Zest: A bit of lemon zest in the filling brightens the flavor.
- Make Ahead: Bake the pie a day in advance and glaze before serving.
Why You’ll Love It
- Feeds a crowd—perfect for potlucks and picnics
- Easier than a traditional pie—no fluting or deep dish drama
- Sweet-tart flavor with a crisp, buttery crust
- Gorgeous presentation with minimal effort
Would you like a gluten-free or vegan version of this slab pie? I’d be happy to adapt it for you!