Raspberry-Rhubarb Slab Pie brings together tart rhubarb and sweet raspberries in a buttery, golden crust. I love how it captures the essence of summer fruit pies, but in a format that’s perfect for sharing. It’s easy to slice, easy to serve, and always a hit at gatherings.
Why I Love This Recipe
There’s so much to love about this pie:
- The raspberry and rhubarb combination offers the perfect sweet-tart balance.
- It's great for serving a crowd—more pie with less fuss.
- The flaky homemade crust pairs perfectly with the juicy filling.
- I can easily customize it with different fruits or toppings.
Ingredients
(Here's a tip: Check out the full list of ingredients and measurements in the recipe card below.)
- All-purpose flour
- Salt
- Unsalted butter, cold and cubed
- Egg yolk
- Milk
- Granulated sugar
- Cornstarch
- Fresh or frozen raspberries
- Fresh or frozen rhubarb
- Confectioners’ sugar
- Vanilla extract
Directions
- Make the Dough: I mix the flour and salt in a large bowl, then cut in the cold butter until the mixture resembles coarse crumbs. I whisk together the egg yolk and milk, then slowly add it to the flour mix to form a dough. I divide the dough into two portions (one slightly larger), wrap them in plastic, and refrigerate for at least an hour.
- Roll Out and Line the Pan: I roll out the larger portion of dough to fit a 15x10x1-inch baking pan, pressing it into the bottom and up the sides.
- Prepare the Filling: I mix sugar and cornstarch in a bowl, then gently toss in the raspberries and sliced rhubarb until coated.
- Assemble: I spread the filling evenly over the crust. Then I roll out the remaining dough and lay it on top. I fold and seal the edges and prick the top with a fork.
- Bake: I bake the slab pie at 375°F (190°C) for 45 to 55 minutes, until the crust is golden and the filling is bubbling.
- Cool and Glaze: After letting the pie cool, I whisk together confectioners’ sugar, vanilla, and a little milk to make a glaze. I drizzle it over the top before cutting the pie into squares.
Servings and Timing
This slab pie makes about 20 to 24 squares. Prep time is around 30 minutes (plus chilling time for the dough), and baking takes 45–55 minutes. It’s usually ready to serve in about 1 hour and 30 minutes.
Variations
- Switch the Berries: I like swapping raspberries with strawberries or blackberries for a slightly different flavor.
- Add Citrus Zest: A bit of lemon or orange zest in the filling brightens the pie beautifully.
- Crumb Topping Option: Sometimes I skip the top crust and use a crumb topping instead for extra texture.
Storage and Reheating
I store leftovers in an airtight container at room temperature for up to 2 days, or in the fridge for up to 4 days. To reheat, I warm slices in the oven at 350°F for about 10 minutes. It helps keep the crust crisp. I don’t recommend freezing it once baked, but the unbaked dough and fruit filling can be frozen separately.
FAQs
Can I use frozen fruit?
Yes, I can use frozen raspberries and rhubarb. I make sure to thaw and drain them well to avoid excess moisture in the filling.
How do I prevent a soggy crust?
To keep the bottom crisp, I make sure the fruit is well-drained and avoid overfilling. A light dusting of cornstarch on the crust before adding the filling helps absorb moisture too.
Can I make this pie ahead of time?
Absolutely. I often bake it a day ahead and let it cool completely. I wait to add the glaze until just before serving for the freshest look and taste.
Can I use store-bought pie crust?
Yes, if I’m short on time, two standard pie crusts (rolled to fit the slab) will work. Homemade gives the best flavor, but store-bought is a good shortcut.
How do I know the pie is done baking?
I look for a golden brown crust and bubbling fruit filling peeking through the slits in the top. That’s how I know it’s cooked through and ready.
Conclusion
Raspberry-Rhubarb Slab Pie is one of my favorite desserts to make when I need something beautiful, easy to serve, and packed with flavor. The mix of sweet and tart fruit in a flaky crust, topped with a drizzle of icing, always hits the spot. Whether for a picnic, party, or just a weekend treat, this pie delivers every time.
Raspberry-Rhubarb Slab Pie
- Prep Time: 30 minutes (plus 1 hour chill time)
- Cook Time: 45–55 minutes
- Total Time: ~1 hour 30 minutes
- Yield: 20–24 squares
- Category: Dessert
- Method: Baking
- Cuisine: American
- Diet: Vegetarian
Description
Raspberry-Rhubarb Slab Pie is a sweet-tart dessert made for sharing, featuring a flaky homemade crust filled with juicy raspberries and rhubarb. Baked in a sheet pan and finished with a vanilla glaze, this easy-to-slice pie is perfect for parties, potlucks, or anytime you want a crowd-pleasing treat with fresh summer flavor.
Ingredients
- For the Crust:
- 3 cups all-purpose flour
- ½ tsp salt
- 1 cup (2 sticks) unsalted butter, cold and cubed
- 1 egg yolk
- ½ cup milk
- For the Filling:
- 1 cup granulated sugar
- ¼ cup cornstarch
- 3 cups raspberries (fresh or thawed if frozen)
- 3 cups rhubarb, sliced (fresh or thawed if frozen)
- For the Glaze:
- 1 cup confectioners’ sugar
- 1 tsp vanilla extract
- 1–2 tablespoon milk
Instructions
- Make the Dough: In a large bowl, mix flour and salt. Cut in the cold butter until the mixture resembles coarse crumbs. In a separate bowl, whisk egg yolk and milk together, then stir into the flour mixture to form a dough. Divide into two portions (one slightly larger), wrap in plastic, and refrigerate for at least 1 hour.
- Line the Pan: Roll out the larger dough portion and fit it into a 15x10x1-inch baking sheet, pressing it into the corners and up the sides.
- Prepare Filling: In a bowl, mix sugar and cornstarch. Gently toss in the raspberries and rhubarb until evenly coated.
- Assemble Pie: Spread fruit filling over the crust. Roll out the remaining dough and place over the top. Seal edges and prick the top crust with a fork.
- Bake: Bake at 375°F (190°C) for 45–55 minutes or until the crust is golden and filling is bubbling.
- Cool & Glaze: Let the pie cool completely. Whisk together glaze ingredients and drizzle over the cooled pie before slicing into squares.
Notes
- Swap raspberries for strawberries or blackberries for variation.
- Add lemon or orange zest to the filling for extra brightness.
- A crumb topping can be used instead of a top crust.
- Use store-bought pie dough if pressed for time.
- Store covered at room temp for 2 days or refrigerated for up to 4 days.
