Raspberry-Rhubarb Slab Pie: Juicy, Tangy, and Perfect for Sharing

Nothing says spring and summer quite like the vibrant flavors of raspberries and rhubarb. This Raspberry-Rhubarb Slab Pie combines the tartness of rhubarb with the sweetness of raspberries in a luscious filling, all nestled in a flaky, buttery crust. The large slab format makes it easy to serve a crowd, perfect for potlucks, family gatherings, or weekend treats. This rustic dessert is impressive, delicious, and surprisingly easy to make!

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Why You’ll Love This Recipe

1. Balanced Flavors: Sweet raspberries paired with tart rhubarb create a perfectly balanced filling.
2. Flaky, Buttery Crust: Homemade pie dough yields a tender, golden crust that complements the fruit beautifully.
3. Easy to Share: The slab format means no cutting multiple pies—serve directly from the baking sheet.
4. Customizable: Add chopped nuts like walnuts or almonds for extra crunch, or sprinkle coarse sugar on top for a decorative finish.
5. Make-Ahead Friendly: Pie dough can be prepared in advance and stored in the fridge or freezer.

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Ingredients

For the Crust

• 3 cups all-purpose flour
• 1 tablespoon granulated sugar
• 1 teaspoon salt
• 1 cup (2 sticks) unsalted butter, cold and cubed
• ½ to ¾ cup ice water

For the Filling

• 4 cups sliced fresh rhubarb (about 1 lb)
• 2 cups fresh or frozen raspberries
• ¾ cup granulated sugar (adjust based on fruit sweetness)
• ¼ cup light brown sugar
• 2 tablespoons cornstarch
• 1 teaspoon lemon juice
• ½ teaspoon ground cinnamon
• ¼ teaspoon salt

For the Egg Wash and Topping

• 1 large egg, beaten with 1 tablespoon water
• Coarse sugar (optional)

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Step-by-Step Instructions

Step 1: Make the Pie Dough

1. In a large mixing bowl, whisk together flour, sugar, and salt.
2. Add the cold, cubed butter. Use a pastry cutter or your fingers to work it into the flour until the mixture resembles coarse crumbs with some pea-sized pieces of butter remaining.
3. Gradually add ice water, one tablespoon at a time, mixing gently with a fork until the dough comes together. Avoid overworking.
4. Divide the dough in half, shape into disks, wrap in plastic, and refrigerate for at least 1 hour (or up to 2 days).

Step 2: Prepare the Filling

1. In a large bowl, combine sliced rhubarb, raspberries, granulated sugar, brown sugar, cornstarch, lemon juice, cinnamon, and salt.
2. Stir gently to coat the fruit evenly.
3. Let the mixture sit for 15–20 minutes to allow juices to release, then stir again.

Step 3: Assemble the Pie

1. Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
2. On a floured surface, roll out one disk of chilled dough into a rectangle about 1/8-inch thick. Transfer it to the prepared baking sheet.
3. Spread the fruit filling evenly over the dough, leaving a 1-inch border on all sides.
4. Roll out the second disk of dough and place it over the filling. Crimp or fold the edges to seal.
5. Brush the top with egg wash and sprinkle coarse sugar if desired. Cut a few slits to allow steam to escape.

Step 4: Bake the Pie

1. Bake in the preheated oven for 35–45 minutes, or until the crust is golden and the filling is bubbling.
2. Remove from the oven and allow it to cool for at least 20 minutes before slicing.

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Tips for a Perfect Slab Pie

• Keep Butter Cold: Cold butter creates a flaky, tender crust.
• Adjust Sweetness: Taste your filling—raspberries and rhubarb vary in sweetness, so adjust sugar as needed.
• Prevent Soggy Bottom: Place the pie sheet on a larger baking pan to catch any juice that may overflow.
• Make Ahead: Dough can be made a day ahead, and fruit filling can be prepped in advance.
• Optional Enhancements: Add chopped walnuts or pecans to the filling for extra texture.

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Variations

1. Mixed Berry Slab Pie: Substitute raspberries with blueberries or blackberries.
2. Nutty Slab Pie: Sprinkle walnuts or almonds over the filling before topping with the second crust.
3. Spiced Slab Pie: Add ginger or nutmeg for extra warmth and flavor.
4. Gluten-Free Version: Use a 1:1 gluten-free flour blend in place of all-purpose flour.

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Serving Suggestions

• Slice into squares or rectangles for easy serving.
• Pair with vanilla ice cream or whipped cream for a decadent dessert.
• Serve alongside coffee or tea for brunch or afternoon gatherings.
• Ideal for picnics or potlucks, as the slab format travels well and is easy to portion.

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Health Benefits

• Rhubarb is rich in vitamins K and C and dietary fiber.
• Raspberries provide antioxidants, vitamin C, and manganese.
• Homemade crust allows control over butter content and sugar, making it a better alternative to store-bought pies.

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Frequently Asked Questions (FAQs)

Q1: Can I use frozen raspberries?
Yes! Just thaw and drain them slightly to avoid excess liquid.

Q2: Can I make this pie vegan?
Yes! Replace butter with vegan butter and use a flax or chia egg wash.

Q3: How do I prevent the top crust from burning?
Cover with foil halfway through baking if edges brown too quickly.

Q4: Can I make mini slab pies?
Absolutely! Divide the dough and filling into smaller sheets for individual pies.

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Conclusion

This Raspberry-Rhubarb Slab Pie is the perfect balance of sweet, tart, and buttery goodness. Its rustic charm, bold flavors, and easy-to-serve format make it a show-stopping dessert for family gatherings, holidays, or summer parties. With a flaky crust and luscious fruit filling, it’s a timeless recipe you’ll return to again and again.