Raspberry Rhubarb Slab Pie
This raspberry rhubarb slab pie is a crowd-feeding spring dessert with a flaky buttery crust, a vibrant sweet-tart fruit filling, and a light vanilla icing drizzle. Baked in a sheet pan, it slices into 24 perfect portions — ideal for gatherings, potlucks, and seasonal celebrations.
Equipment
- Large Mixing Bowl
- pastry cutter or knives
- Rolling Pin
- 15x10-inch jelly roll pan
- whisk
- wire rack
Ingredients
- 3 cups all-purpose flour
- 1 tsp salt
- 1 cup cold butter, cubed
- 1 egg yolk
- 180 ml milk (plus extra if needed)
- 4 cups raspberries, fresh or frozen (thawed and drained)
- 3 cups rhubarb, sliced
- 1.5 cups granulated sugar
- 0.33 cup cornstarch
- 1 cup confectioners' sugar
- 1 tsp vanilla extract
- 2-3 tbsp milk (for icing)
Instructions
- In a large bowl, whisk together flour and salt. Cut in cold butter until the mixture resembles coarse crumbs with pea-sized pieces.
- Whisk egg yolk with milk, then gradually add to the flour mixture, mixing until the dough just comes together.
- Divide dough into two portions (one larger), wrap, and refrigerate for at least 1 hour.
- Preheat oven to 375°F (190°C). Roll out the larger dough and fit into a 15x10-inch pan.
- Mix sugar and cornstarch, then toss with raspberries and rhubarb. Spread evenly over crust.
- Roll out remaining dough and place over filling. Seal edges and prick top with a fork.
- Bake for 45–55 minutes until golden brown and bubbling. Cool completely on a rack.
- Whisk confectioners' sugar, vanilla, and milk to make icing. Drizzle over cooled pie, slice, and serve.
Notes
Chill the dough thoroughly before rolling to ensure a flaky crust. Always drain frozen fruit well to avoid a watery filling. Let the pie cool completely before slicing for clean squares. Adjust icing consistency carefully for the perfect drizzle.